802 Transactions of the American Institute. 



tissus, comparables aux pet its vegetaux des levures ordinaires, sont 

 aussi les decompositours des substances qui les environment." 



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 

 fundamental identity with the ultimate structural elements of vegeta- 

 ble organisms. 



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

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

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

 variously modified ; and tending 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 repre- 

 sents, in the simplest fashion, the process which is repeated by every 

 cell of the living body." 



In other words, Schawnn 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 

 development, 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 Torulm which 

 float in beer-wort. 



