II. 



CYTOMORPHOSIS.* 



Your Magnificence! 

 Gentlemen! 



We endeavored in yesterday's lecture to familiarize our- 

 selves with the new cell doctrine, according to which a much 

 greater importance is attributed to the composition of the 

 living substance than to the fact that this substance has a 

 strong tendency to form cells; all the same, cells remain the 

 most convenient units of biological research, although they 

 can by no means be found always completely separated from 

 one another. But even if the cells are not separated, it is 

 practical and convenient to designate each nucleus, together 

 with its surrounding protoplasm, as a cell. Every fully 

 formed tissue of the animal body has at least one character- 

 istic kind of cells, or in other words the cells of a tissue exhibit 

 among themselves similar relations and similar structure. 

 Hence we can direct our attention to the single cell which we 

 value as the paradigma. 



In man, as in the great majority of multicellular ani- 

 mals, development begins with simple cells which arise by the 

 segmentation of the ovum. From the simple cells the tissues 

 of the adult develop gradually. As I told you yesterday, we 



* The term cytomorphosis was proposed by me in 1901. The corresponding 

 conception- was first definitely propounded in the Middleton Goldsmith Lecture, 

 published in 1901. This lecture has recently appeared in the German translation in 

 my book "Die Methode der Wissenschaft" (Gustav Fischer, Jena). My book 

 "The Problem of Age, Growth and Death" (New York, Putnam's, 1908), treats of 

 cytomorphosis in some detail, although in somewhat popular form. 



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