STUDIES ON FERMENTATION. 



185 



fermentation and increasing the proportion of yeast. On March 

 19th we made a fresh sketch, which it is not necessary either 

 to reproduce ; suffice it to say, that the yeast was now consider- 

 ably more regular and uniform in appearance. 



Spontaneous ferment, therefore, very often occurs in this large 

 ferment-form, which, by repeated developments in the act of fer- 

 mentation, becomes reduced by degrees after successive genera- 

 tions to the ferment which, following Dr, Rees, we have named 



Fig. 38. 



saccharomyces j^d^^orianus, a polymorphous ferment which must 

 be studied closely that it may not be confounded with others, 

 inasmuch as it is so universally diflPused that we very seldom 

 fail to find it in any ferment which has been exposed in contact 

 with ordinary air, at least, we may repeat, in a laboratory 

 devoted to researches on fermentation. We have found tbe 

 same thing occur in a brewery, being there mixed with the 

 ferments used in brewing. 



There are, no doubt, several varieties of this saccharomyces. 

 We sometimes find amongst the spontaneous ferments which 

 repeated growths have brought to a more or less uniform state, 

 the forms represented in Plate XI., but the cells and segments 

 much smaller. Amongst others, Dr. E,ees has distinguished a 

 saccharomyces exiguus. 



Fig. 38 represents another spontaneous ferment, which 

 appeared in a boiled saccharine wort, which entered into fer- 

 mentation after being exposed to the air of the laboratory. 



