Not infrequently, histories of cell theory will mention Jan Purkyně (1787–1869) and his student Gabriel Gustav Valentin (1810–1883) as important forerunners to Schleiden and Schwann. Years before Schleiden’s 1838 “Beiträge zur Phytogenesis” and Schwann’s 1839 Mikroskopische Untersuchungen, Purkyně and Valentin both observed nuclei in animal cells, and both suggested a possible homology between plant cells and animal cells. Purkyně never wrote any essay, book, or treatise just on cell theory the way that Schleiden and Schwann had, but Valentin did exactly that in 1835.
Probably fewer than 10 people have ever read Valentin’s 1835 treatise on cells, however. According to historian Erich Hintzsche, Valentin’s Histiogeniae plantarum atque animalium inter se comparatae specimen (A comparative study of histogenesis in plants and animals) consists of over 1,000 handwritten quarto pages in Latin, along with 45 hand-drawn plates. It was apparently not written with publication in mind. In 1833 the Académie des Sciences in Paris announced a competition for the Grand prix des sciences physiques for 1835, with the following prompt to compare the development of tissues across plant and animal species:
Examine whether the mode of development of organic tissues in animals can be compared to the way in which tissues of plants develop. Recall, on this occasion, the various systems of the physiologists, repeat their experiments and see to what extent they agree with the rules of reasoning and the general laws of organization. Above all, ascertain whether the lower animals develop in a different way from the higher animals; additionally, whether there exists as many such differences in the growth of acotyledons, monocotyledons and dicotyledons, as some authors assert; finally, whether there are at the same time several modes of growth among the dicotyledons.*
*: Examiner si le mode de développement des tissus organiques chez les animaux, peut être comparé à la manière dont se developpent les tissus des végétaux. Rappeler, à cette occasion, les divers systèmes des physiologistes, répéter leurs experiences et voir jusqu’à quel point elles s’accordent avec les règles du raisonnement et les lois générales de l’organisation. S’assurer surtout si les animaux d’un ordre inférieur se développent d’une autre manière que ceux d’un ordre supérieur; s’il existe aussi dans l’accroissement des acotylédones, monocotylédones et dicotylédones, alltant de différences que l’ont quelques auteurs; enfin si chez les dicotylédones il y a à la fois plusieurs modes d’accroissement.
Valentin submitted Histiogenia comparata in January 1835 won the Academy’s 1835 Grand prix, which came with a financial reward of 3,000 francs. The cash allowed Valentin to purchase his own Schiek & Pistor microscope (made in Berlin) liberating him from needing to borrow Purkyně’s even more costly Plössl microscope (made in Vienna). The honor allowed Valentin to leave Purkyně’s institute in Breslau (Wrocław) in 1836, when the University of Bern offered him a full professorship in physiology, where he became the first, non-converted Jewish Ordinarius at a German-speaking university. The Academy asked Valentin to shorten the manuscript for publication, and in 1837 he submitted a revised and shortened draft, still in Latin. However, this was also never published, and in 1838/39 Schleiden and Schwann would write and publish their own, groundbreaking cell theories—in German, rather than Latin.
Both Valentin’s 1835 and 1837 manuscripts are apparently deposited in the archives of the Académie des Sciences, or possibly with the library of the Academy’s parent institution, the Institut de France. Of the speculations for why Valentin never published his Histiogenia comparata the most convincing to me is that neither Valentin nor his mentor Purkyně actually believed that animal cells and plant cells were essentially the same: for Purkyně and Valentin (and Schleiden!) the similarities between plant and animal cells were superficial, whereas for Schwann and us today the similarities are fundamental.
As I mentioned, the number of people who have ever read Valentin’s Histiogenia comparata in the original, handwritten Latin is very low. Purkyně surely read it before Valentin submitted the manuscript in January 1835. The 1835 Académie jury consisted of Mirbel, Blainville, Magendie, Étienne Serres, and Adolphe-Théodore Brongniart. In 1939 Miloš Volf looked the manuscript briefly, for an event commemorating the centenary of Schleiden and Schwann’s cell theory. In 1962 the aforementioned biographer of Valentin, Erich Hintzsche, examined both the 1835 and the 1837 manuscripts in detail. In 1963 Hintzsche published a ca. 100 page précis of Valentin’s manuscript as vol. 20 of his own monograph series, Berner Beiträge zur Geschichte der Medizin und der Naturwissenschaften. In addition to ca. 6 pages explaining the history of the Histiogenia comparata itself, 2 pages of illustrations, and about 60 pages in German summarizing the manuscript, Hintzsche also gives us 30 pages of excerpts in Latin, appended as endnotes.
For the most part, historians have only bothered to mention Valentin’s Histiogenia comparata insofar as he won the Academy’s Grand prix by writing about cells 3–4 years before Schleiden and Schwann became famous for doing the same. As far as I am aware, nobody since Hintzsche has written anything new about Valentin’s Histiogenia comparata, and it’s possible that almost nobody else has since tried to look at the original 1835/37 manuscripts in Paris. There aren’t even that many historians who have read Hintzsche’s 1963 précis. It turns out that Valentin’s (and, by extension, Purkyně’s?) ideas about cell structure, function, and formation are both weird and complicated. Even though few of Schleiden and Schwann’s ideas about cells held up for more than a decade, at least their theories had the benefit of being simple and forceful—they had left to other biologists the work of sorting out the details of how cells actually work.
Because the Berner Beiträge zur Geschichte der Medizin und der Naturwissenschaften is hard to find and definitely not digitized, I’ve decided to scan Hintzsche’s 1963 Zellen und Gewebe in G. Valentins “Histiogenia comparata” von 1835 und 1838 and make it available for here for people to download and read. My scan is not particularly high quality; if you need something in higher resolution, email me and I’ll see what I can do. Hintzsche himself wrote a short biography of Valentin in 1953, and this and the older literature is cited in the bibliography of Valentins “Histiogenia comparata”. My more recent sources of information are G. Rudolph, “Gabriel-Gustav Valentin (1810–1883): Grand prix de l’Académie des science (1835) correspondant de l’Académie de médecine (1846),” Histoire des sciences médicales 19, no. 4 (1985): 367–75; and Henry Harris, The Birth of the Cell (New Haven: Yale University Press, 1999), chapter 9.
p.s.: If you happen to know exactly where the original 1835/37 manuscripts are, please send me an email or leave a comment. In my brief search I could not figure out whether they were being held by the Bibliothèque de l’Institut de France or the Archives of the Académie de Sciences, as the catalogues for both institutions turned up blanks for me.
Update 17 September 2022: I managed to misspell “Histiogenia” by dropping the second “i”—Histogenia instead of Histiogenia. I’ve corrected that now. But, I’m not the only one! Henry Harris and G. Rudolph also had spelled it “Histogenia.” I do not know Latin grammar, and so if it turns out that it is “Histogenia” and not “Histiogenia” then please email me or leave a comment.