AGGREGATION IN THE TENTACLES OF DROSERA. 811 



be seen at once. This was the case with the cell shown in 

 fig. 6; the appearance of the object changed as it was being 

 drawn, so that it would have been impossible to draw the 

 whole cell. By Avhatever cause aggregation is induced, it 

 commences in the gland and spreads from cell to cell down 

 the tentacle. On the other hand, when, on the cessation of 

 the stimulus which has induced aggregation, the masses of 

 crimson matter gradually dissolve and the cells become once 

 again filled with homogeneous crimson fiiuid, the process of 

 dissolution travels from cell to cell up the tentacle. 



The above brief description may serve as an introduction 

 to a discussion in which the various features of the phe- 

 nomenon will be considered in greater detail. 



The first questions which arise are — What is the nature 

 of the aggregated masses, and with what parts of a typical 

 vegetable cell are they homologous ? 



In the course of his description of the aggregated masses, 

 my father remarks '} " Their movements are rather slow, and 

 resemble those of Amoeba or of the white corpuscles of the 

 blood. We may, therefore, conclude that they consist of 

 protoplasm." And in his subsequent discussion he always 

 speaks of the aggregated masses as protoplasm. My father's 

 assumption will appear justifiable to many; nevertheless 

 more than one eminent physiologist have expressed doubts on 

 this point. Professor Ferdinand Cohn in his review of * In- 

 sectivorous Plants '~ always speaks of aggregation as a " mass- 

 ing together (Zusammenballung) of the red sap " and never 

 calls the masses protoplasm. Any opinion even hinted at by 

 so eminent an authority deserves the most careful considera- 

 tion. And since the question whether the aggregated masses 

 are condensations of protoplasm or precipitations of cell-sap 

 is of the utmost importance in determining the true nature 

 of the phenomena of aggregation, it seems worthy of dis- 

 cussion. Before entering on the question it must be premised 

 that the phenomena cannot possibly be considered as purely 

 a mechanical or chemical one, like the running together of 

 oil-drops into larger drops ; the minute and continuous 

 changes oi form, and the separation into secondary masses 

 absolutely negative such a view. Moreover the changes are 

 subject to the general conditions to which protoplasmic move- 

 ments are subject. It follows therefore that the changes 

 not being mechanical must be vital, i. e. due to the movement 

 of living protoplasm. If, then, we accept Professor Cohn's 

 view that the masses of aggregated matter are passive con- 



1 P. 40. 



=■ 'Deutsche Rundschau,' ii, 9, 1876, p. 454. 



