THE CYTOPLASM AND ITS DIFFERENT PRODUCTS 39 



(nuclear vacuole of Wagner). Sometimes in the long yeast cells 

 (S. Ludwigii, Sch. Pombe and mellacei, Mycoderma) it possesses 

 two such vacuoles situated at both ends of the cell and separated by 

 a sort of very dense cytoplasmic bridge in which the nucleus is 

 situated. (Fig. 47, 5.) In the course of development other vacuoles 

 may appear at the side of these and include glycogen, giving the cell 

 an alveolar appearance. At the same time, the cytoplasmic struc- 

 ture which limits these vacuoles is filled with numerous grains of 

 various forms and sizes which 

 are colored in the same 

 manner as the nucleus which 

 we have called " basophile 

 grains." Finally, droplets of 

 fat are also often seen. 



The cytoplasm is then 

 the seat of numerous secre- 

 tions: metachromatic 

 granules, glycogen, basophile 

 grains, and fats. The char- 



cm. 



acters of these special prod- 



Fig. 47. Yeast Cells with Nuclei (n) and 

 Metachromatic Corpuscles (cm). From a 

 Stained Preparation. 



1-4, S. cerevisiae, beginning of fermentation; 5, S- Lud- 

 wigii, beginning of fermentation; 6-10, evolution of 

 UCtS Will nOW be taken Up. metachromatic corpuscles during sporulation. 



A. Metachromatic Granules: The metachromatic granules, which 

 were first studied by Guilliermond, 1 constitute the most impor- 

 tant elements which are found in yeasts. They seem to play a 

 very important role in cellular life. These bodies are almost ex- 

 clusively localized in certain vacuoles, be it in a regular vacuole 

 occupying the middle of the cell or in two polar vacuoles. They are 

 able to exist also in the cytoplasm which surrounds the vacuoles. 

 It is there that they seem to originate elaborated by cytoplasm and 

 probably with the participation of the nucleus, because it is almost 

 always in contact with the vacuoles. Once elaborated by the cyto- 

 plasm, they localize in the vacuoles, at whose expense they enlarge, 

 in order to eventually dissolve at the time of their utilization. The 

 metachromatic corpuscles are easily visible in living cells where they 

 appear as refractive particles in the vacuoles, and seem to possess a 

 Brownian movement. They may be fixed in the living condition by 

 such dyes as methylene blue, neutral red, toluidin blue, etc. 



1 Guilliermond, A. Recherches sur la structure de quelques champignons 

 inferieurs. Comp. Rend. Acad. Sci. 133, 1901. 



Guilliermond, A. Recherches histologiques sur la sporulation des levures. 

 Comp. Rend. Acad. Sci. 133, 1901. 



Guilliermond, A. Recherches cytologiques sur les levures et quelques 

 moissures a forme levures. Thesis for the Doctorate at the Sorbonne, Storck, exit. 

 Lyon, 1902. 



