Guilllermond - Atkinson 



180 



Cytoplasm 



off and forms the small vacuole of the daughter cell. Dangeard 

 has sought more recently to demonstrate, but this time with vital 

 dyes, that the vacuoles of algal zoospores are always transmitted 

 by means of the filament put out at germination. 



In Saprolegnia, growing on media to which neutral red has 

 been added and observed in van Tieghem and Le Monnier cells, 

 we have shown, however, that the vacuoles which in the zoospores 

 appear as small granules, fuse at the moment of germination to 

 constitute a single large vacuole and then, in the germination tube, 

 small globular vacuoles appear which do not seem to be derived 

 from the large vacuole of the zoospore. Now, if the objection of 

 Pierre Dangeard is sound in regard to vital staining of the 

 ordinary fungi which, when carried out between slide and cover 



* > a • ■ • 7 • 



A 



* a J • 1 1 



Fig. 125 (left). — Saprolegnia. Germination of zoospores in a van Tieghem 

 and Le Monnier cell on 1% peptone bouillon with 0.001% neutral red. 1, 2, 

 zoospore. 3-20, germination tube. The large vacuole extends into the germina- 

 tion tube and may fuse (15) with small vacuoles which form at the tip. (After 

 Mile. Cassaigne) . 



Fig. 126 (right). - 

 vacuoles during budding 

 cell without vital dyes, 

 mentation and fusion. 

 vacuole of mother cell, 

 formed by a kind of 

 Cassaigne) . 



- Saccharomyces pastor ianus. Types of formation of 

 of the yeast grown in a van Tieghem and Le Monnier 



A, 1-8, Observation during 1 hr. 1-5, successive frag- 

 6, 7, prolongation sent into bud. 8, separation from 



B, vacuole of bud formed de novo. C, vacuole of bud 

 budding from vacuole of mother cell. (After Mile. 



glass do not grow as long as they keep the neutral red accumulated 

 in their vacuoles, this objection is evidently not sound in the case 

 of Saprolegnia, which can be grown on media to which neutral 

 red has been added. Mile. Cassaigne repeated this study and ob- 

 served the development of vacuoles, both in the germination tube 

 and in the growing filaments. She was able to see small vacu- 

 oles form de novo which later refused to constitute a single large 

 vacuole, or elongated into filaments and anastomosed into a net- 

 work. Nevertheless, since the conditions of observation were ad- 

 mittedly abnormal because of the presence of neutral red. Mile. 

 Cassaigne repeated the work of P. Dangeard on the yeasts in 

 which she followed budding without vital staining. Now, she ob- 

 served that actually the vacuole of the bud may arise from the 

 budding of the vacuole of the mother cell, as Dangeard indicated, 

 but that often this vacuole also arises de novo in the bud. 



These observations seem therefore to furnish proof that these 

 vacuoles form de novo. In consequence of our research, we have 



