5S2 THE POPULAR SCIENCE MONTHLY. 



1838, Turpin compared the Tondce to the ultimate elements of the 

 tissues of animals and plants. The elementary organs of their tissues, 

 which might be compared to the minute vegetable growths found iii 

 common yeast, are likewise decomposers of those substances which en- 

 viron them. 



Almost at the same time, and, probably, equally guided by his 

 study of yeast, Schwann was engaged in those remarkable investiga- 

 tions into the form and development of the ultimate structural ele- 

 ments of the tissues of animals, which led him to recognize their fun- 

 damental identity with the ultimate structural elements of vegetable 

 organisms. 



The yeast-plant is a mere sac, or " cell," containing a semifluid 

 matter, and Schwann's microscopic analysis resolved all living organ- 

 isms, in the long-run, into an aggregation of such sacs or cells, vari- 

 ously modified ; and tended to show that all, whatever their ultimate 

 complication, begin their existence in the condition of such simple 

 cells. 



In his famous " Mikroskopische Untersuchungen " Schwann speaks 

 of Torula as a " cell," and, in a remarkable note to the passage in 

 which he refers to the yeast-plant, Schwann says : 



I have been unable to avoid mentioning fermentation, because it is the 

 most fully and exactly known operation of cells, and represents, in the simplest 

 fashion, the process which is repeated by every cell of the living body. 



In other words, Schwann conceives that every cell of the living 

 body exerts an influence on the matter which surrounds and permeates 

 it, analogous to that which a Torula exerts on the saccharine solution 

 by which it is bathed a wonderfully suggestive thought, opening up 

 views of the nature of the chemical processes of the living body, which 

 have hardly yet received all the development of which they are 

 capable. 



Kant defined the special peculiarity of the living body to be that 

 the parts exist for the sake of the whole, and the whole for the sake of 

 the parts. But when Turpin and Schwann resolved the living body 

 into an aggregation of quasi-independent cells, each like a Torula, 

 leading its own life and having its own laws of growth and develop- 

 ment, the aggregation being dominated and kept working toward a 

 definite end only by certain harmony among these units, or by the 

 superaddition of a controlling apparatus, such as a nervous system, 

 this conception ceased to be tenable. The cell lives for its own sake, 

 as well as for the sake of the whole organism ; and the cells, which 

 float in the blood, live at its expense, and profoundly modify it, are 

 almost as much independent organisms as the Toruloe which float in 

 beer-wort. 



Schwann burdened his enunciation of the " cell-theory " with two 

 false suppositions : the one, that the structures he called " nucleus " 



