288 FERMENTATIONS IN MILK 



Bouillon. In ordinary peptone broth little development occurs, 

 but it grows rapidly in glucose peptone solution. 



b. The second species, described as the " non-motile Granulo- 

 bacillus saccharobutyricus," is a common organism in milk, 

 dung of farm animals, and human faeces ; it is also abundant in 

 water, soil, and the meal of cereals. 



Two varieties exist, one a long cylindrical bacillus with 

 rounded ends, often in chains three to six together ; the other 

 a smaller and shorter organism, rarely united in chains. 



Both are strictly anaerobic. 



In the fermentation of milk-sugar, and carbohydrates by these 

 organisms, lactic as well as butyric acid is formed, often in 

 larger quantity than the latter compound. 



Granulose is present in the growing cells, but generally absent 

 from those in which spores are formed : this ^ubstance is most 

 abundantly produced when the organism is supplied with starch, 

 little or none being made when sugar is supplied. 



The spores withstand boiling for an hour and a half. 



Gelatine media are liquefied. 



Agar. Surface colonies on slightly alkaline agar, containing 

 i grain of starch or sugar per litre, are smooth and shining, 

 irregular in outline in the case of the long variety, rounder and 

 more watery in the short-celled form. 



Milk is rendered acid: the casein is coagulated but not 

 peptonized ; it becomes full of gas bubbles. 



Bouillon containing 2 per cent, of starch or grape-sugar is a 

 good medium for the growth of this organism, but spores are not 

 produced in it. 



Ex. 139. To obtain Clostridium-forms of Granulobacillus 

 saccharobutyricus, the following receipt, suggested by Beijerinck, 

 gives successful results : 

 Put in a flask : 



Cane-sugar . . . . 10 gr. 



Finely-ground fibrin . . . .10,, 



Precipitated calcium carbonate . 6 



