26 ILLINOIS DAIRYMEN'S ASSOCIATION. 



tic fermentation, says: "At the present time a large number of species 

 (over one hundred) have been described as producing the acid fermenta- 

 tion in milk. To what extent, however, they are all to be regarded as 

 producing lactic acid, we can hardly say, because in most cases no at- 

 tempt has been made to determine chemically the presence, of lactic 

 acid, the investigator ordinarily being contented with the determination 

 of The production of an acid reac-tion." Even if 4t were known that all 

 produced lactic acid, it would be very doubtful if the percent of acid is 

 exactly the same for each species, taking for granted that the conditions 

 under which the reastions took place were exacly the same. 



Another acid quite frequently met with is buytric acid, produced by 

 bacillus buytrics. These are met with as frequently as the germ pro- 

 ducing lactic acid and it was formerly supposed this was a contamina- 

 tion of the latter. 



The viscosity of milk is often greatly increased by the action of 

 bacteria; it may become so marked as to produce "slimy" or "ropy" 

 milk, that is, the milk will be so sticky that when touched with the fin- 

 gers long threads of milk will adhere to them. 



Another very disagreeable taint is produced by a certain species of 

 bacteria imparting a bitter taste to the milk. 



The soapy flavor caused by a yet different species occurs very sel- 

 dom. 



Milk may be curdled through the action of bacteria without the pro- 

 duction of acids. These forms produce renrjet, which coagulates the milk. 



The production of color is, however, much more common than some 

 of these other taints. The red pigment in milk, produced by B. pro- 

 digiosus, is often mistaken for blo3dy milk. This same form is the 

 cause of small red or bloody spots in bread, frequently the cause of 

 much superstition. A blue color in miilk, produced by B. cyanogenes, is 

 not uncommon and yellow and green are sometimes met with. 



The putrification of milk is caused by species of bacteria attacking 

 the albuminoids, producing various substances, among them the plam- 

 aines, some of which are very pois mous. This process of decomposi- 



