" It is not to be imagined, however, that the whole of the credit is due to Schwann. 

 Much had been done before his time by the English botanist, R. Brown, who discovered 

 the nucleus in vegetable cells, in 1831; by Schleiden ; by G. Valentin, who dis- 

 covered the nucleolus in 18.36 ; Henle, Purkinje, and many others, but the soil was 

 ready, and Schwann grasped the situation at the psychological moment. His theory 

 as to the origin of cells from a ' blastema ' was, however, nothing more than an 

 ingenious, but utterly fallacious speculation. This doctrine of Schwann's was absolutely 

 denied by Virchow, who paraphrasing the original statement of Redi and Harvey, 

 ' omne vivum KX oi-o,' said ' omnis cellula n cellula,' i.e., every cell comes from a pre- 

 existing cell. After 1840 a period of great activity set in, marked by the work of 

 Martin Barry, R. Remak, J. Goodsir, Naegeli, Max Schultze, L. Beale, Leydig, Kolliker, 

 and many others upon the structure and mode of development of the cell. Schwann, 

 like Bernard, did his great work early in his career." 



Twenty years later it was reserved for the now venerable 

 R. VIRCHOW, who celebrated his eightieth birthday on 12th October 

 last, to apply the doctrine to the 

 production of cells under abnormal 

 conditions. 



" His famous work on Cellular Pat/toloyy 

 was published in 1858 the year in which the 

 ' Theory of Natural Selection ' was propounded 

 independently by Darwin and Wallace. The 

 second edition, translated by Chance, was 

 dedicated to John Goodsir. Gocdsir, indeed, 

 in 1845, had shown that the nucleus divides, 

 and is the ' germinal centre of the cell.' Both 

 Martin Barry and R. Remak had noticed 

 division of the nucleus in 1841." (W. S. in 

 Jfed. Chronicle, 1901.) 







SCHWANN S ORIGINAL FIGURE OP 

 MUSCLE AND NERVE. 



Schwann's work was published 

 in 1839, and became available for 

 English readers as Microscopical Researches into the Accordance in the 

 Structure and Growth of Animals and Plants, by Th. Schwann, trans, 

 by H. Smith, F.R.C.S. (Sydenham Soc., 1847). 



M. J. SCHLEIDEN. 



1804-1881. 



THE names of Schleiden and Schwann are linked together in 

 connection with the cell-theory. The former was born at 

 Hamburg in 1804, studied at Heidelberg from 1824 to 1827, 

 when he graduated as Doctor of Laws. In 1833, he studied medicine 

 in Gottingen, and then went to Berlin and, under his uncle Horkel, 

 applied himself to natural science, but especially to botany. In 1839 



