EXPERIMENT STATION BULLETINS. 205 



it may be grown. Another species will produce ropy or stringy milk 

 by changing the milk sugar into a viscous form and again we will have 

 other species acting upon the albuminous substances, it may be the casein 

 of the milk, changing them into a slimy mass. 



If we should isolate several species which are commonly present in 

 milk and allow them to grow for a long period in milk, unassociated with 

 any other species, we would find after several weeks that there would 

 be some producing a condition of the milk which would be slimy and 

 even ropv in many cases. From this we would conclude that ordinarily 

 there are found in milk, bacteria which would give rise to either 

 ropy or slimy milk, provided all the conditions were favorable to their 

 development. 



It is fortunate, however, that there are desirable germs which gain 

 the ascendency over these undesirable germs, therefore they are usually 

 unable to manifest their presence. Whenever we find species which 

 grow more rapidly than the lactic acid bacteria, we are then made aware 

 of their presence by their actions upon the milk and only then do we 

 meet with ropy or slimy milk. 



SOAPY MILK. 



A peculiar condition of milk is that of soapiness. Upon handling it, 

 it responds much like soft soap. An instance of this kind was reported 

 by a dairyman in Illinois, who said that if his whev tanks were not 

 scalded, his whey would appear like soft soap upon dipping. Several 

 other occurrences of this nature are recorded in literature, but it is 

 necessary to say only that these circumstances are brought about by 

 specific micro-organisms which have a tendency in their action upon 

 milk to convert it into a soapy condition. In my work in the laboratory, 

 I have found bacteria isolated from milk which would produce the 

 above condition. These bacteria seem to act upon the casein and 

 albumin. ' ■ j ', j il 



. ■ .* < 



POISONOUS MILK. 



We have satisfied ourselves thus far that bacteria are able to act 

 upon milk in diverse ways. Some of their actions we regard as benefi- 

 cial, while others as sorely detrimental. In the consideration of the 

 production of poisons by bacteria, we must bear constantly in mind 

 that although this phase of bacterial action stands out very prominently 

 and has a peculiar interest, it is simply coordinate with the other mani- 

 festations of bacteria in milk. Instead of having lactic acid or butyric 

 acid as the product of bacteria, we have an intense poison, hardly com- 

 parable with poisons known to us. Vaughan, of the University of Mich- 

 gan, has the credit of being the first to isolate a poison called tyrotox- 

 icon, which is perhaps the most common of bacterial poisons in milk. 

 It was originally found in cheese, from which it took its name, but it has 

 been repeatedly found in milk, ice cream and cheese. In "Ptomains and 

 Leucomains," the authors, Vaughan and Novy, have cited several cases 

 of milk poisoning. In one case, "on August 7, twenty-four persons, at 

 one of the hotels at Long Branch, were taken ill soon after supper. At 

 another hotel, on the same evening, nineteen persons were seized with 



