ALCOHOLIC FERMENTS. 



183 



in the brewery). This behaviour is undoubtedly related to 

 a phase in the development of yeast-cells which HANSEN 

 discovered in 1884. He found that not only the Saccharo- 

 mycetes but also other budding-fungi are able to secrete a 

 gelatinous network, which can be seen as threads or plates, 

 and in which the cells lie embedded (Fig. 46, A, B). If, for 





FIG. 46. Yeast cells with gelatinous network (after HANSEN) : J, network obtained 

 by partial drying ; 1, portion formed of threads, from which the cells have become 

 detached ; 2 and 3 show that the network can also form complete walls ; such a 

 formation is seen between a and 6 ; a, is a vegetative cell, b is a cell with two spores ; 

 4, shows three cells, a, embedded in the network. B, network with yeast cells, the 

 latter stained by methyl-violet ; the network is not stained. Some of the yeast cells 

 are still in the meshes, but most have detached themselves. 



example, a moderately thick paste of brewery yeast is 

 placed in a glass and allowed to remain under cover in such a 

 way that it slowly dries, and then a trace of this yeast is mixed 

 with water, the network can be clearly seen (Fig. 46, A). 

 The formation also occurs in the gypsum block and gelatine 

 cultures. The author has frequently observed this remarkable 

 formation, after HANSEN had called attention to its nature, in 

 the yeast samples which are sent to his laboratory in filter- 



