206 THE PRESERVATION OF MILK. 



diffused, but they do not develop below 18 C. Milk sterilised 

 by mere boiling may therefore be rich in such bacteria and yet 

 keep unaltered for a long time at room temperature, though, if 

 introduced into the alimentary canal of the young infant, the 

 hardy spores develop into rapidly-multiplying bacilli which decom- 

 pose the constituents of the milk. In such case, not only are 

 copious amounts of gas, giving rise to considerable flatulency, 

 formed, but also poisonous decomposition products of albuminoid 

 matter, which when fed to puppies produce diarrhoea attended 

 with fatal results. 



The danger incurred from this cause is much greater for the 

 nursing infant than for the adult, not only because the latter 

 organism is stronger, but also for the further reason that the 

 dietary of adults is a mixed one, in consequence whereof numerous 

 other bacteria, inimical to those in question, are introduced into 

 the alimentary canal. On the other hand, the result of using 

 such imperfectly and partially sterilised milk is that the digestive 

 organs of the infant, nourished on milk alone, are converted into 

 a veritable breeding-ground for these poisonous microbes. 



These bacteria are closely allied to the Bacillus mesentericus 

 vulgatus. Fliigge himself described a number of such species ; 

 and S. STERLING (I.), added five new ones to the series, naming 

 them with reference to their chemical activity as Bacillus lactis 

 peptonans a, /3, y, S, . Attention was drawn at an earlier date, 

 by LOEFFLER (III.) and Emma Strub, to the frequent occurrence 

 of B. mesentericus vulgatus in milk. 



Attempts have not been lacking on the part of dairy techni- 

 cists and bacteriologists to arrive at a method for annihilating 

 these pests as well. A critical examination of these methods 

 cannot, however, be made here, but any reader desiring fuller 

 details is referred to a comprehensive exposition of the question 

 compiled by H. WEIGMANN (II.). At present, merely a single 

 example will be given, namely : 



126. The Method of Neuhauss, Gronwald, and 

 Oehlmann, 



which was tested by PETRI and MAASSEN (II. ). We have already, 

 in a previous section, demonstrated that it is not easy to render 

 milk sterile in the strict meaning of the word. The high and 

 long-continued heating necessary thereto is sufficient to alter the 

 chemical constitution of the milk in such a manner that it becomes 

 almost unsuitable for nutrition. The lactose, as P. CAZENEUVE 

 and HADDON (I.) have shown, decomposes into dark brown fission 

 products (containing formic acid), with an empyreumatic flavour ; 

 the fat loses its emulsified condition and separates out as cream, 

 which cannot be made to diffuse again even by shaking ; and the 

 albuminoids are converted into a form very difficult of digestion. 



