102 PRELIMINARY COLD STORAGE STUDIES. 



the expense of the digested casein. The rapidity with which this digestion takes 

 place vanes in different samples, but at the expiration of two weeks it is pronounced. 



What the effect of the low temperatures is on the carbohydrate constituents of the 

 milk remains for further study. That an interesting decomposition, and one which 

 varies from that occurring at higher temperatures, takes place is indicated by the 

 very high acid content of the milk noted throughout this investigation. 



Similar studies, conducted on samples of very fresh milk kept at the temperature 

 of the laboratory (about 18 to 22 C.), show a very decided difference chemically 

 from the decomposition of milk in cold storage. Bacterial growth at room tempera- 

 ture is, of course, rapid and profuse. The acid-forming organisms are, as has been 

 found by other observers, in high proportion and the liquefying organisms are rela- 

 tively lower. The chemical change observed is, by comparison with that occurring 

 in cold storage, almost nothing. At the curding point only about 1 per cent of the 

 casein has been changed to soluble products, and spontaneous curding is observed, 

 ordinarily, when the acid content falls between 23 and 28 ce of tenth-normal sodium 

 hydrate per 100 cc. 



CHICKENS. 



The results obtained show unmistakable evidences of bacterial 

 activity during the period of storage. While naturally the frozen 

 condition of the flesh prevents to a great extent bacterial migra- 

 tion, it does not prevent absolutely bacterial growth. It is perfectly 

 certain from these experiments, as well as from others, to which ref- 

 erence has been made, that a degree of cold, equivalent to that sus- 

 tained in ordinary cold storage, does not by any means destroy bac- 

 teria. The effect is simply to produce a state which may be described 

 somewhat broadly as suspended animation. It is also certain in some 

 instances that the number of bacteria may be diminished during cold 

 storage, showing that while cold does not kill all species of bacteria 

 it may hold certain forms in suspended animation so long that they 

 are finally killed. 



Attention should be called also to the fact that as this line of work 

 was entirely new, a great deal of the time has been devoted to deter- 

 mining the best methods for the investigation and' establishing the 

 general principles on which it should be based. It is evident, there- 

 fore, that the deductions which are to be drawn here are only to be 

 considered of a tentative nature and should not be regarded as the 

 final word on the subject. Too few specimens have been examined 

 to make the data sufficiently extensive to be relied upon as a final 

 basis of conclusions. The experiments have undoubtedly been car- 

 ried on under conditions which are more favorable than those exist- 

 ing in the markets in general. 



The fowls on which the work conducted at Washington was done 

 were specially selected, killed with the greatest care, packed with the 

 utmost precautions, and in every way subjected to the cleanest con- 

 ditions. On the contrary the fowls which are ordinarily placed in 

 cold storage are not selected fowls, they have not been killed and 

 prepared with special care, nor are any special means taken to pre- 



