THE METHOD OF NEUHAUSS, ETC. 159 



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 (contain- 

 ing 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. 



Neuhauss, Gronwald, and Oehlmann, calling to mind the information afforded 

 by the fractional method of sterilisation, sought to induce the hardy spores to 

 germinate, in order that the end in view might then be attained by moderate 

 means. With this object the milk is placed in bottles with loose-fitting stoppers, 

 which are then put into a specially constructed case, where they are surrounded 

 by steam and allowed to remain for half an hour at a temperature of 8o-95 ^ 

 This so-called preliminary sterilisation is once repeated, with the result that the 

 pathogenic and the lactic acid bacteria are destroyed, and the milk is then 

 left to cool gradually, whereby it passes through the degrees of temperature 

 favourable to the germination of the surviving hardy spores. On the following 

 day the samples are subjected (in the same bath) to the so-called chief sterilisation 

 at 102 C., and when this is finished the stoppers of the bottles are immediately 

 and simultaneously tightened up by means of an arrangement manipulated from 

 the outside. The instructions given to adhere to a temperature of 102 C. prove 

 that the germination of the spores is not numerically complete, since, it' this 

 were the case, a maximum of 100 C. would suffice for the chief sterilisation, all 

 the vegetative forms quickly perishing at this temperature. If, h .wever, spores 

 be still present at the commencement of the chief sterilising process, the 

 probability is by no means small that they will also be able to withstand the 

 short exposure to 102 C., and it may be anticipated that even this method will 

 not always accomplish its object. As a matter of fact, reports are not wanting 

 e.g. that of M. BLEISCH (I.) to the effect that milk samples assumtd to have 

 been sterilised by the method in question have been subsequently discovered to 

 be in a state of decomposition ; whilst Fliigge was unable to confirm the 

 favourable reports given by Petri and Maassen, and PICTET and WEYL (I.). 



In short, there is at the present time no practicable and certain method for 

 freeing milk (on a large scale) from germs without at the same time seriously 

 prejudicing its flavour and nutritive value. Since, then, the annihilation of the 

 hardy germ.s in this case is so difficult, attention is now directed to their 

 exclusion from the milk ; the greatest care is therefore taken by washing the 

 udder, hands, and milk vessels to secure extreme cleanline s in the preparation 

 of "nursery milk" intended for infant consumption. The so-called sterilisation 

 then becomes a much easier task, the milk, drawn with such precaution from the 

 cow, being very poor in the above-mentioned gas-forming bacteria. As a ready 

 means of detecting the presence of these organisms will often be useful to the 

 scientific adviser of a Dairy Association, the fermentation flasks described by 

 F. SCHAFFEE (I.),Tn. SMITH (1. and II.), and others, are therefore recommended 

 for the regular examination of the milk supplied by the individual farmers 

 as regards its content of the pests under consideration, 



