io8 Transactions of the Canadian Institute. [Vol. VII. 



Hay bacillus types were found only six times out of eleven analyses. 

 Agar surface plates were used for isolating these germs as they favoured 

 the growth of this group of micro-organisms. 



The remaining analyses agreed very closely with the above; on one 

 occasion, however, the large number of 100,000,000 lactic acid bacteria 

 per gramme were found in cheese ten days old. 



In addition to these analyses, a number of cheese were made with 

 starters made from the microbes isolated during the investigation, as 

 well as many of Duclaux's Tyrothrix forms. The experimental cheese 

 were compared with control ones ; and in most cases the ripening was 

 not normal. In conclusion, de Freudenreich drew the following con- 

 clusions from his observations and experiments : 



1. Those often looked upon as prime factors in the ripening of 

 cheese — the gelatine liquefying bacilli (Tyrothrix, Potato, or Hay 

 bacillus) are not numerous in cheese, and generally not in milk. 



2. Far from multiplying in the cheese, they seem, even if added to it 

 in great quantities, to die off rapidly, unless when added in the spore 

 form, in which case they remain alive for a longer time, but without 

 multiplying. 



3. Added to milk set for cheese, they seem neither to produce 

 fermentation nor favour it. 



4. Probably various lactic ferments play the principal, if not the only 

 part, in the ripening of Emmenthaler cheese. In the soft cheese, on 

 the contrary, Oidiuin lactis, and also yeasts, take part in the ripening. 



Under the heading of " Character and Variability of species of 

 Tyrothrix," VV. Winkler found after an examination of species of 

 Tyrothrix that, " whilst some, as T. tenuis, were more allied to the hay 

 and potato bacilli, others as T. urocephaluin and T. filiformis were more 

 nearly connected with the granulo-bacteria. They adapted themselves 

 with great ease to different nutrient media, and their characters thereby 

 became altered. In milk, they were more or less peptonizing. Butyric 

 acid was only produced by a few of them. Milk sugar favoured their 

 growth, but seemed to interfere with their peptonizing power." Three 

 varieties of Tyrothrix tenuis were cultivated: (i) a form which 

 peptonized milk and liquefied gelatin ; (2) a form which produced 

 lactic acid, but did not liquefy gelatin ; (3) a fluorescing type which 

 formed a red pigment on potato. 



Winkler stated that, '"Bacillus xvi, Adametz, which was undoubtedly 



