Guilliermond - Atkinson — 222 — Cytoplasm 



technique. It has no marked affinity for ferric lake, but can be 

 stained by other processes (with cresyl blue, haematein and other 

 dyes), which give the vacuoles a typical reddish color characteristic 

 of metachromatin. 



It is possible, on the other hand, to stain both the chondriome 

 and the vacuolar system at the same time in living material, by a 

 mixture of Janus green and neutral red, and then it can be observed 

 that the two systems are always coexistent and have no genetical 

 relationship whatever. There is, therefore, between the vacuoles 

 which are shaped like chondriosomes and the chondriosomes them- 

 selves, only a similarity of form, which doubtless represents a 

 somewhat closely related physical state of these two categories of 

 elements. In some lower algae, the vacuoles do not undergo hydra- 

 tion and during the entire development of the cells persist as 

 numerous semi-fluid inclusions, scattered about in the cytoplasm, 

 analogous to those which characterize the embryonic state of cells 

 of higher plants. The vacuoles of animal cells seem to be of this 

 type. In other algae, on the contrary, the vacuoles are always 

 large liquid vacuoles. 



The vacuoles, in all stages of their development, almost always 

 contain colloidal substances dispersed in their sap and vital stain- 

 ing of the vacuoles is connected with the presence of these sub- 

 stances. These substances, however, vary in nature according to 

 the type of cell and correspond to the products secreted by the cell. 

 There is no substance characteristic of vacuoles as there is of 

 chondriosomes. Often there are encountered in the same cell 

 two categories of vacuoles, always independent of each other, made 

 distinct by their colloidal content. In other cases there are en- 

 countered, side by side in a single cell, vacuoles with colloidal con- 

 tents and others seeming not to contain any colloidal substance 

 whatever. These latter seem to have no predilection for vital 

 dyes, yet seem to be derived from the former by a phenomenon of 

 syneresis or of coacervation. 



Although almost always represented in plant cells, and capable 

 of fragmenting, the vacuoles seem to arise de novo. It may be sup- 

 posed that their formation is, in general, connected with secretory 

 phenomena of the cell. Each colloidal granule secreted by the 

 cytoplasm, possessing a capacity for taking in water which is 

 greater than that of the cytoplasm, seems capable of engendering 

 a vacuole. There are, as well, many other inclusions but they are 

 purely transitory and dependent on the physiological state 

 of the cell. These are products arising from cellular metabolism. 



Thus the cell can be made to fit into a general plan which 

 applies to every cell, animal as well as plant, with the exception of 

 the Cyanophyceae and the bacteria. These facts bring out strik- 

 ingly the extreme complexity of the morphological constitution of 

 the cytoplasm which appears to us as a colloidal system in which 

 the chondriosomes, the plastids and the vacuoles constitute so 

 many distinct phases. The cytoplasm is, therefore, a colloidal 

 system of a very heterogeneous structure. 



