FOOD OF YEAST 67 



use for such masses of yeast plant has been suggested. 

 The yeast mass must contain considerable food material, 

 and the question has been raised whether it is not pos- 

 sible to utilize it as a food product. By simple means 

 extracts of such yeasts have been made and have lately 

 been placed upon the market. These materials, known 

 as ovus, wuk, and siris, have not yet appeared in America 

 but are found in the European trade. They have a value 

 almost the same as that of ordinary beef extracts. They 

 make an appetizing bouillon which may be a useful stimu- 

 lant, but since they are only extracts, they contain practi- 

 cally no real food. They may therefore easily take the 

 place of such substances as Liebig's beef extract and similar 

 products, but like them they do not contain real food and 

 must not be regarded as nutritious. 



