394 THE HISTORY OF BIOLOGY 



In the special section of the handbook Schleiden gives an explanation 

 of the cytology, morphology, and physiology of plants, after much the 

 same plan as has been followed in similar works since then. This method of 

 presentation really bears the stamp of genius; the actual contents, however, 

 offer nothing essentially new from the point of view of that age; with con- 

 stant and often extremely abusive criticism of the botanists of the time — 

 Brown and Mohl are the only ones who are let off lightly — he presents a 

 summary of the facts already known. Concerning the formation of the cell 

 he propounds his old theory, although by that time it had lost much of the 

 validity it formerly possessed. In fact, another scientist had entered this 

 field of research with an entirely new idea that eventually directed its fur- 

 ther line of development. 



Theodor Schwann was born in 1810 in a small town in Rhenish Prus- 

 sia, where his father had a book-shop. He studied under his fellow-country- 

 man J. Miiller, at both Bonn and Berlin; having taken his doctor's degree, 

 he became his master's assistant. In 1839 he was called to the chair of anat- 

 omy at the Roman Catholic University of Louvain, and some years later to 

 Liege, where he worked until shortly before his death, in iSSz. He was of a 

 gentle and reserved disposition; he avoided polemics and therefore accepted 

 none of the professorships that were offered to him at German universities — 

 he did not like the way the German histologists quarrelled, he said — and 

 throughout his life he remained a devout Catholic; thus, he was in every- 

 thing a contrast to Schleiden, with whom nevertheless he was on friendly 

 terms. His scientific activities fall entirely within the period during which 

 he worked with Miiller; it apparently needed his master's will-power to 

 spur his easy-going and peaceful nature on to any exertion. As a professor he 

 published only some few text-books and summaries. His teaching was always 

 conscientiously carried out. 



Schwann's work on cell-structure 

 Schwann's research work during hh Berlin period was both many-sided 

 and important. His doctor's dissertation dealt with the respiration of the 

 embryo of the chick; he discovered the ferment of gastric juice, to which he 

 gave the name "pepsin"; he studied Infusoria and experimented with fer- 

 mentative phenomena, which led him to deny spontaneous generation and 

 to declare that fermentation and putrefaction are caused by organisms. All 

 these works, however, fall into the shade beside that by which he established 

 his fame as one of the pioneers of biology — the work published in 1839 en- 

 titled: Mikroskopische Untersuchungen tiber die Ubereinstimjnung in der Struktur 

 und dem Wachstum der Tiere und Pflan':(en. He here takes as his starting-point 

 Schleiden's above-mentioned cell-formation theory, which he accepts in its 

 entirety and expands into a general theory of the basis and origin of life- 

 phenomena. By way of introduction he points out the fundamental difference 



