4.1. Cândido Firmino de Mello-Leitão

Born in 1886 in Campina Grande, Paraíba, Cândido Firmino de Mello-Leitão graduated in 1909 from the Medicine School of Rio de Janeiro. In 1913, Mello-Leitão held a public tender for the position of professor of General Zoology at the High School of Agriculture and Veterinarian Medicine of Rio de Janeiro, where he was the principal from 1915 to 1919 and remained until his retirement. He was a Zoology professor at the National Museum of Rio de Janeiro from 1931 to 1937 and at the National Faculty of Philosophy of the Universidade do Brasil from 1939 to 1941 (^{SANTOS, 2013}). He held the position of vice president (1937 - 1939) and president (1943 - 1945) of the Brazilian Academy of Sciences and served in the Ministry of Agriculture (1930 and 1940) as a member and president of the National Council of Fishing and Hunting and as a consultant for Zoogeography matters of the National Council of Geography (^{FRANCO; DRUMMOND, 2007}).

Mello-Leitão specialized in the study of arachnids and described new species, publishing around two hundred scientific articles in specialized journals on Arachnida taxonomy between 1915 and 1951. To honor Edgar Roquette-Pinto, he named a new species of spider Roquettea singularis. Also, to honor his friend and botanist Alberto José de Sampaio, he named a scorpion Tytius sampaiocrulsi. Throughout his life, Mello-Leitão cataloged 59,000 species of invertebrates (DUARTE, 2009; 2010).

Mello-Leitão stood out for his activism alongside other intellectuals to promote the association of Biology with Education, relating it to the conservation and protection of fauna and flora and to aspects that linked to the hygiene of the population. Acting as a researcher at the National Museum of Rio de Janeiro and as a professor at Instituto de Educação do Distrito Federal, Mello-Leitão sought to disseminate scientific knowledge to the lay public (DUARTE, 2009). According to ^{Spiguel and Selles (2013}), in times of popularization of scientific knowledge, we understand that Mello-Leitão defends Biology, proposing changes in the teaching of Natural History in school education.

4.2. Lafayette Rodrigues Pereira

A former Colégio Pedro II boarding school student, Lafayette Rodrigues Pereira had the highest scores in the selection exams to be the Natural History chairperson of Colégio Pedro II, being sworn in as a full professor in 1918.

The Brazilian physician and writer Pedro Nava (1927 - 1984) narrates in his memoir, Chão de Ferro, his experiences during sessions taught by Professor Lafayette Rodrigues Pereira during the years he spent as a student at the Colegio Pedro II boarding school - where he remained from 1916 to 1920.

Natural history was previously taught only in the fifth grade until one class before mine. Then it was decided that from 1919 the subject would be split into two academic years. On this occasion, Leite took office, and we saw him prepping with Ennes de Souza to start his classes. But death did not allow it. His position was open for dispute. Preparation and luck favored Lafayette Rodrigues Pereira, a young doctor who, despite his name, had no kinship to the counselor’s family. [...] When the school year began, we found Lafayette excited and ready to start sessions. The first one he taught us was his debut as a teacher at Colégio Pedro II. At the appointed time, we stood up and saw a young man with a protruding forehead enter the room, brown hair thrown back in studied negligence, blue eyes like two turquoise beads, light brown skin, an upturned, well-made nose with twitching nostrils, and a Bel Ami mustache. [...]. Thus and wearing a high collar, plastron, striped pants, gaiters, and varnish shoes - Lafayette impressed us deeply (^{NAVA, 2012}, p. 286-287).

Lafayette R. Pereira also held the positions of vice-principal and principal of the boarding school, retiring after 33 years at this institution.

4.3. Waldemiro Alves Potsch

Waldemiro Alves Potsch (1892 - 1968) graduated in Medicine and began his career at Colégio Pedro II, in 1917, as a Geography teacher in a supplementary class for the 1st grade of day school and later applied for the position of professor of Natural History in 1918, second best after Lafayette Rodrigues Pereira in the selection exams. As a substitute teacher, Waldemiro Potsch taught Natural History and Portuguese. He was the Natural History chairperson in the day school of Colégio Pedro II in 1925 and joined the school congregation from its inauguration until the 1960s. With an extensive publication of textbooks from the 1920s to 1970s, Waldemiro Potsch’s intellectual production is mainly related to the school subjects of Natural History and Physical and Natural Sciences (^{SANTOS, 2013}).

Several of his didactic works were recommended in the curriculum of Colégio Pedro II, and possibly other educational institutions, indicating his influence on the history of the subject Natural History in Brazil (^{SANTOS, 2013}). Waldemiro Potsch fathered three children who later became Biology teachers at Colégio Pedro II: Paulo Potsch, Carlos Potsch, and Sylvio Potsch (^{CASSAB, 2011}).

5.1. The compendiums by Candido de Mello-Leitão

The analysed books authored by Candido de Mello-Leitão in this study were: Noções de Biologia Geral (1930) [General notions in Biology] (Figure 1), Curso elementar in História Natural (vol. 4, 1935) [Elementary Course in Natural History] (Figure 2), and Compendio Brasileiro de Biologia (v.1, 1943) [Brazilian Compendium of Biology] (Figure 3).

Mello-Leitão’s book Noções de Biologia Geral, published by Livraria Francisco Alves, has 339 pages in the format 14 x 22 cm (Figure 1). The definition of life is discussed in the first chapter, comprised of six pages (p.7-12). Mello-Leitão begins chapter 1 entitled “Definitions, Domain, and Method of General Biology” stating that Biology “[...] is the science that studies living beings”, enumerating some among so many other divisions of this field of study. Then, referring to the term “Biology,” the author states that this “[...] has no exact meaning of its own”, attributing to this the fact that the study of life involves very different points of view (ibid, p.7).

Source: National Museum of Rio de Janeiro collection.

Figure 1 Front cover of Noções de Biologia Geral (1930). 

Source: National Museum of Rio de Janeiro collection.

Figure 2 Front cover of Curso Elementar de Historia Natural (vol. 4, 1935). 

Source: Author’s private collection.

Figure 3 Front cover of Compendio Brasileiro de Biologia (v.1, 1943). 

“LIFE” is the title of the third subsection (from a total of six) in chapter 1. In it, the author states that “by studying living beings, biology begins to meet the idea of what life is.” However, it readily clarifies that “in the present state of science, this definition cannot be more than an essay.” Soon after, the author mentions the possibility of life being defined as the relationship between living beings and the environment, characterized by two essential phenomena: self-regulation and the continuation of the species (ibid, p.9). Mello-Leitão concludes that:

Each living being has its own chemical individuality and a specific, microscopic, and ultramicroscopic architecture. They also have the ability for growth, reproduction, and development. Finally, they have their own conduct, a record of excitations or experiences [...] and variability (^{MELLO-LEITÃO, 1930}, p.9).

In these excerpts from the third subsection, Mello-Leitão highlights that, although the study of living beings can bring answers to what “life” is, such definition “cannot be more than an essay,” referring to its complexity.

Regarding the possibility of life being defined as the relationship between living beings and the environment, having as essential factors the self-regulation and the continuation of the species, we can understand that the idea of “self-regulation” is directly linked to the definition of autopoiesis, while the “continuation of the species” is closer to the definition of life as the natural selection of replicators.

While concluding the subsection “LIFE,” enumerating some characteristics of living beings, Mello-Leitão used a common practice in current Biology textbooks, which was to differentiate living beings from inanimate beings using a list of characteristics. This is another element of the traditional view on the definition of life, in which life can be defined or at least differentiated from raw matter through a list of underlying properties.

The book Curso Elementar de Historia Natural (vol. 4, 1935), published by Companhia Editora Nacional⁴, has 424 pages with a 14 x 22 cm format (Figure 2). In chapter 5, entitled Life and living beings (p. 43 -55), we find content from the first chapter of Notions in General Biology (1930). This chapter was revised and expanded to a total of 13 pages to include topics not present in the initial chapter of the former book. Mello-Leitão begins the chapter with the definition of Biology:

Biology is the science of life. In its broadest sense, it includes all the knowledge that has been accumulated, referring to living beings. By a curious coincidence, the word biology was used independently by two naturalists - LAMARCK and TREVIRANUS - in the same year of 1802, as an appropriate definition to designate the science of living organisms. It is much easier to define the science of life than life itself. [...] efforts to define life are as futile in improving our knowledge as the diligence to define space, time, matter, and many other common phenomena of our daily experience (^{MELLO-LEITÃO, 1935}, p.43).

Among the ideas that characterize the traditional view on the definitions of life, two can be identified: (1) life cannot be defined; (2) the definition of life is not an important issue for biology. Next, the author describes (ibid, p. 44-49) the characteristics specific to living beings that differentiate them from raw matter: complex and heterogeneous chemical constitution; variability; growth; regeneration; development; reproduction; sensitivity and mobility. We also found a third idea about the traditional definition of life: (3) The process of life can be defined or at least differentiated from physical processes or raw matter through a list of underlying properties.

In the view of the author of this compendium, if life cannot be defined or if conceptualizing it is irrelevant, the important thing is to characterize the “living” through attributes or particularities that differentiate it from the “non-living.” Such ideas remained in the 20th century and are treated as a traditional view of the definition of life (^{EMMECHE; EL-HANI, 2001}).

The work Compendio brasileiro de biologia (vol. 1, 1943), published by Companhia Editora Nacional, has 423 pages with a 14 x 22 cm format (Figure 3). In chapter 1, entitled Biology: treatise of living beings and comprising 18 pages, Mello-Leitão discusses basic concepts of Biology and clarifies that this “[...] is the science that studies living beings”. Next, the author refers to the definition of life: “Life has not yet found a satisfactory definition, and so we prefer to define Biology as the science that studies living beings, instead of giving the etymological notion of the science of life” (Mello-Leitão, 1943, p. 7).

If for the “science of life” there is the challenge of finding a definition for its object of study - life, the same is not valid for the “science that studies living beings,” which enumerates and describes the particularities common to living beings which allows them to be differentiated from raw matter: cell structure, complex chemical constitution, metabolism, irritability, reproduction, evolution, among others. Mello-Leitão deals with the science that studies living beings in 15 pages of this chapter, approaching the third idea of the traditional view on the definition of life. The remaining part of the chapter deals with issues surrounding the origin of life.

5.2 The compendiums by Lafayette Rodrigues Pereira

The analysed compendiums authored by Lafayette Rodrigues ^{Pereira were: Zoologia [Zoology], published in 1930} (Figure 4) and Botanica [Botany], published in 1931 (Figure 5).

Zoologia (1930), authored by Lafayette Rodrigues Pereira and printed by Tipografia A Encadernadora S. A., has 805 pages in a 13 x 18 cm format (Figure 4). In the introductory chapter - Prolegomena, the author states that “[...] it is customary to divide the beings studied by Natural History into two kingdoms: - the living and the dead, or the organized and the inorganic” (^{PEREIRA, 1930}. p.7). In this case, when discussing the “realm of the dead,” Lafayette is referring to minerals.

Source: NUDOM Collection.

Figure 4 Zoologia Cover (1930). 

Source: Author’s private collection.

Figure 5 Botanica Cover (1931) 

In Prolegomena, a subsection entitled: General laws of life, comprised of 11 pages (ibid, p. 10 - 20), the author discusses the science of life:

Numerous are the differences between living bodies and inorganic beings, or, in other words - there are biological properties that do not allow for confusion between living organism and inorganic beings. Physiology is what describes and analyses these properties; it is the science of life (^{PEREIRA, 1930}, p.10).

The “inorganic beings” to which the author refers are the raw minerals and matter. Lafayette continues: “What is life? This is a difficult question to answer” (ibid., p. 10). First, the author clarifies that “[...] countless thinkers, biologists, philosophers and attentive observers of nature, have tried to explain the notion of life in a short proposition. However, efforts are fruitless, and criticism often dismisses the defining arrangements” (ibid., p.10). Next, the author presents a metaphysical view as an answer to the question:

As Claude Bernard said, life is not a principle that demands an objective existence; the word does not correspond to an entity; it is a metaphysical expression. In fact: the term life expresses, in a laconic way, the synthesis of the work of organized matter and... nothing else. All vital phenomena are linked to certain physicochemical conditions; if these conditions are met, life remains; otherwise - it does not (^{PEREIRA, 1930}, p.11).

This author’s statement that: “[...] the term life expresses, in a laconic way, the synthesis of the works of organized matter, and ... nothing else” is similar to Ernest Mayr’s idea when he claims life to be “[...] simply the objectification of the processes of life” (^{MAYR, 1998}, p. 95; 2008, p.19-20). If such physical-chemical processes occur, life remains; otherwise, life ceases to exist. Lafayette ^{Pereira (1930}, p.11) continues stating that attempts to define life are old and have existed since Hippocrates. Some consider it a principle, while others, a result but “[...] all definitions are erroneous, or insufficient”, reinforcing the idea that life cannot be defined. Pereira, in his article “Life,” published in the Journal Humanidades, reaffirms that life cannot be explained while discussing the ideas of different scientists and concludes:

There are no hypotheses or materialistic theories that can be accepted as an explanation to the origin of life in our planet. At most, we could speculate about the environment in which life began, in light of the evolutionary history of the Earth, as well as the study of the structure of beings or their traces found in the first stratifications of the lithosphere (^{PEREIRA, 1947}, p. 63).

The compendium Botanica (1931) by Lafayette Rodrigues ^{Pereira was printed in 1931} in Officinas Graphicas ALBA, with 627 pages and in a 13 x 18 cm format (Figure 5). On the cover, it is written: “Elementary compendium adopted at Colégio Pedro II and in numerous educational establishments of the Republic.” In the introductory chapter -Prolegomena , there is a subsection entitled: “Characterization of living beings; differences between living and brute beings” (p.10-20). Lafayette opens the subsection by discussing living beings:

Those who begin the study of biology immediately feel the need to deal with the assumption related to the morphological and dynamic characterization of beings endowed with life, establishing the differences between organized beings and inorganic or crude matter (^{PEREIRA, 1931}, p.10).

Throughout ten pages (ibid, p. 11-20), the author addresses particularities of living beings and contrasts them with the non-living. Unlike his work Zoologia (1930), the definition of “life” is not discussed in the compendium Botanica. In this work, he discusses the characteristics of living beings, approaching the third idea of the traditional view on the definition of life.

This author did not publish Biology compendiums, possibly because the books were published until the early 1930s and Biology only emerged as a school subject for secondary education in classical and scientific courses in the early 1940s, according to the Decree-Law 4.244 of April 9, 1942, and educational programs of 1943 (^{SANTOS, 2013}).

5.3 The Compendiums by Waldemiro Alves Potsch

The examined compendiums authored by Waldemiro Alves ^{Potsch were: Botanica [Botany] (1933}) (Figure 6), Historia Natural para a 4ª serie [Natural History for the 4^th grade] (1937) (Figure 7), Zoologia [Zoology] (1957) (Figure 8) and Compendio de Biologia Geral [Compendium of General Biology] (1959) (Figure 9).

Botanica (1933) was printed by the typography A Encadernadora S.A. The work has 384 pages and a 16 x 23 cm format (Figure 6). In the introductory part, entitled “Characters of living beings” (p.1-5), Potsch begins the paragraph by stating that: “[...] nature, at the simplest inspection, presents beings divided into animals, vegetables and crude or mineral bodies” (ibid, p.1) and goes on to explain how to differentiate these three types of beings:

When beginning the study of botany or zoology, the first inquiry of our spirit is to know the characters that allow us to establish a differentiation between them. Generally speaking, it is easy to point out the characters that make it impossible to confuse a living being, animal or plant, with any mineral of nature. [...] there is no way to hesitate in its classification, which is within reach of any primary school child. There is a set of characters in living beings that are not present in minerals (^{POTSCH, 1933}, p.1).

Source: National Museum of Rio de Janeiro collection.

Figure 6 Botanica Cover (1933). 

Source: National Museum of Rio de Janeiro collection.

Figure 7 Front cover of Historia Natural para a 4ª serie (1937). 

Potsch describes characteristics present in living beings (animals and plants) that are not observed in minerals: cellular structure, permanent activity, absence of shape and geometric dimensions such as observed in minerals, complex chemical structure, nutrition, respiration, reproduction, self-regulation, and limited duration of life, concluding with the differentiation between animals and plants. Neither in the introductory chapter - nor throughout the Botanica compendium - does the author address the definition of “life”; he refers to living beings, describing the characteristics that differentiate “that which has life” from “that which has no life,” aligning himself with the third idea of the traditional definition of life.

Historia Natural para a 4ª serie (1937) was printed by the Estabelecimento Gráfico Apollo in 1937, with 376 pages and a 14 x 19 cm format (Figure 7). The first chapter, entitled Characters of living beings (p.7-15), gathers knowledge explained in the Botanica (1933) compendium. ^{Potsch (1937}) states that nature “presents beings divided into animals, vegetables and crude or mineral matter” (p.7) and describes in six pages (p. 7-12) the set of characters of living beings not found in minerals: cellular structure, permanent activity, absence of shape and geometric dimensions as seen in minerals, complex chemical structure, nutrition, respiration, reproduction, self-regulation and limited duration of life. Next, the author describes the differences between animals and plants (p.12-15). As in Botanica (1933), the author does not discuss the definition of life, and the introductory chapter is intended to describe the characteristics that differentiate living beings from raw matter.

In the work Zoologia (415 pages) (Figure 8), with a 16 x 23cm, published in 1957 by Editora Livraria Francisco Alves, the definition of life was not identified, as in the other two books - Botanica (1933) and Historia Natural para a 4ª serie (1937). Potsch described the characteristics that define living beings and that are not found in raw matter without defining the concept of “life” in these compendiums.

Source: NUDOM Collection.

Figure 8 Zoologia Cover (1957). 

Source: Author’s private collection.

Figure 9 Front cover of Compendio de Biologia Geral (1959). 

The Compendio de Biologia Geral (1959) [General Biology Compendium] (Figure 9) is a publication of Colégio Pedro II, with 263 pages and a 16 x 23 cm format (Figure 9). In this work, the author holds some lines at the beginning of the second chapter (entitled LIFE - p. 15 - 20) to discuss the definition of “life”:

It is easier to talk about the phenomena that characterize life rather than to define it. Philosophers and biologists across time have always sought to define life. Aristotle’s definitions - “life is the set of organic movements of the bodies that possess it,” Bichat’s - “life is the sum of functions that oppose death,” and so many others, are flawed and immediately challenged when proposed. If we cannot define it, we know that life is an attribute of a specific category of beings, which is why we call them living beings. Just as physics studies light, heat, and electricity as forms of energy whose properties are known independently of the bodies that produce, contain, or transmit them, so biology can consider life as an autonomous entity, as a form of energy. Physical and chemical laws are not the creators of life but their instruments, such as matter is only the host of life (^{POTSCH, 1959}, p.15).

Quoting Morales, Potsch refers to “life” as being a form of “energy” or an autonomous entity. Therefore, the living being is the “instrument” or “host of life,” and “life” is an attribute of living beings.

Without going into detail on the type of “energy” in which “life” consists, ^{Potsch (1959}, p.15-16) addresses the nature of vital phenomena: Vitalism, Mechanism, and Neovitalism. In Vitalism, life is “[...] the result of the action of a force or principle acting on organized matter”; in Mechanism, “[...] it seeks to explain the vital manifestations by the physicochemical forces inherent in matter,” being, therefore, the physiological phenomena subordinated to the physicochemical processes occurring in the organism; and in Neovitalism, the author states that “[...] the physicochemical forces cannot be the only factors that regulate vital phenomena” but are also “essential to the existence of an immaterial principle that provides the vital character to organic matter.” Finally, Potsch concludes the chapter with the general characters of living beings (p.16-18) and the differences between animals and plants (p.18-20).

The analysis of the works of the three authors shows they did not explain their own definition of “life” but transcribed definitions by other authors, indicating the complexity of defining it and understanding it as an “attribute of living beings” - carriers of life - and that are not found in raw matter. Roquette-Pinto (1922, p.19) also points out this trend in the thinking of the time when he states that the focus is not to understand what life is, but what a living being is: “But true progress could only be assigned with the displacement of the initial question. It is no longer a question of conceptualizing life, but of verifying what the living being is” (emphasis added).

Three ideas about the definition of life can be found in the analysed compendiums: (1) the complexity of the definition of life: “It is easier to discuss the phenomena that characterizes life than to try to define it” (^{POTSCH, 1959}, p.15); (2) the debates about the definition of life have not led to advances in the teaching of biology: [...] “the efforts to define life are so futile and barely improve our knowledge” (Mello-Leitão, 1935, p.43); (3) the process of life can be defined or at least differentiated from physical processes or raw matter through their underlying properties: “Whoever starts the study of biology immediately feels the need to deal with the assumption related to the morphological and dynamic characterization of beings endowed with life, establishing the differences between organized beings and the inorganic ones” (LAFAYETTE, 1931, p.10).

^{Potsch (1959}), citing Morales, states that, just as Physics studies light, heat, and electricity as forms of energy whose properties are known, Biology can also consider life as an autonomous form of energy, pointing out an idea of life that reinforces Biology as an autonomous science (^{MAYR, 2008}): “Although life is a physical phenomenon, biology deals with systems of such complexity that we cannot hope, in practice, to reduce it to physics” (^{POTSCH, 1959}, p.15).

The concept of life remained unchanged in these three decades in the compendiums of Biology and Natural History analyzed. According to ^{Choppin (2009}, p. 74), as an intellectual construction, the textbook “[...] varies according to the places, times, supports, levels and subjects of education, sometimes with political, economic, social, cultural, aesthetic contexts, but also, and above all, due to the scientific problem in which it is inserted.” Therefore, one can understand that despite being works of different authors, books are texts produced simultaneously and in the same scientific context regarding understanding the phenomenon of life and living beings.

The historical context and socio-political purposes of an era determine the traditions of school subjects (^{GOODSON, 2011}; ^{CHERVEL, 1990}). Thus, the knowledge and the way they are explored reflect the time they are inserted. These teachers who wrote textbooks adapted the contents about life and living beings in their books for the two academic-branded school subjects, with references to foreign authors and scientists. According to Gatti Junior (2005), textbooks in the 1930s-1960s were aimed at an elite and academic audience and written with an elaborate vocabulary. Regarding the way the three authors discussed the definition of life and living beings in the analyzed compendiums, ^{Chervel (1990}) understands that:

In each age, the teaching provided by teachers is roughly identical for the same subject and level. All the manuals, or almost all of them, say the same thing, or almost so. The concepts taught, the terminology adopted, the collection of rubrics and chapters, the organization of the corpus of knowledge, even the examples used, or the types of exercises attempted are identical, with approximate variations (^{CHERVEL, 1990}, p.203).

Mello-Leitão, Lafayette Rodrigues Pereira, and Waldemiro Potsch wrote the compendiums in a socio-historical context of educational reforms and significant development of Biological Sciences. Although Mello-Leitão and Potsch dissent about the subjects Natural History and Biology in secondary education (^{SANTOS, 2013}), the analysis of the compendiums in this study indicated that their ideas were similar when approaching the definition of life, considered complex by the three authors, and on the underlying properties of living beings. In previous studies on textbooks authored by Mello-Leitão and Potsch, approximations were noted in relation to the nationalist character of the works and differences concerning the elucidation of knowledge (SANTOS, 2013; SANTOS; SELLES, 2014). Different perspectives for the analysis of textbooks are fruitful in historical research, revealing nuances in changes and permanence in school subjects.