224 THE ORGANISMS IN YEAST. 



posed to utilise the term Saprophytes to include all organisms con- 

 cerned in putrefactive or fermentative changes, and for the present 

 I propose to adopt it, employing where necessary such distinctive 

 terms as are most generally understood. 



The " Yeast-Plant " of the earlier observers, the Torula cere- 

 vtsice, consists of a spherical or ovoid cell, having an interior 

 albuminous hning containing protoplasm, and an outer coat of 

 cellulose, which may be distinguished by means of re-agents. The 

 protoplasm appears to be devoid of chlorophyll, and in mature 

 samples several small vacuoles and minute spherical bodies, some 

 of which are evidently of an oily nature, are to be observed ; 

 whilst in most cells is a more or less developed spherical vesicle, 

 generally towards one side, and the contents of which are evi- 

 dently liquid. This formation will be seen on reference to the 

 plate, and is especially noticeable in No. 3, which was obtained from 

 a very old stock in a Northern brewery, and less so in Nos. 5 and 

 6, which are from Burton. This vesicle not infrequently contains 

 a remarkably spore-like spherical body, but which, in the majority 

 of specimens, especially from breweries where what is known as a 

 " fast " fermentation is carried on, does not seem to develop fully. 

 In the sample shown at No. 3, and in others from the same 

 source, the cell-wall and the border of the vesicle alike exhibited a 

 degree of firmness ; while the interior spore-like body was large 

 and well developed, and possessed a rapid, gyratory movement 

 within the vesicle. I have on several occasions been fortunate 

 enough to observe this movement, which I believe is hitherto 

 unrecorded, and under a power of some 1,500 diameters it can be 

 watched with the greatest certainty. But I have not been able 

 to satisfy myself as to the manner in which this movement is 

 brought about, although the peculiar jerky gyrations suggests 

 the idea that it is due to the action of cilia or flagella, and if 

 so, suitable illumination will no doubt enable us to detect them.* 

 I have never been able to find any indication of such motion in 

 any specimens of Burton yeast, though I have received a very great 

 number, neither is it usually to be found in the yeasts from the 



* Since writing the above the Author has placed specimens in the hands of a 

 friend, by whom, after careful examination, the movements are pronounced to be 

 undoubtedly due to the influence of heat, and are probably identical with those 

 known as Brownian movements. 



