BUEEAU OF ANIMAL INDUSTRY. 153 



The study of the emaciation in cattle has yielded results of con- 

 siderable interest. The chemical composition of the flesh from a 

 considerable number of carcasses of cattle condemned for emacia- 

 tion was found to differ very markedly from thaf of normal lean 

 beef. The results at hand are a clear indication of an advanced 

 stage of inanition, during Avhich the muscles have suffered marked 

 changes in composition. Feeding tests to determine the nutritive 

 value of the protein from the flesh of emaciated cattle are in progress 

 and a certain amount of chemical work remains to be done. 



An investigation of the rancidity of fats, intended to determine 

 more precisely than is now known the nature of the chemical changes 

 which take place in fats during the process of becoming rancid, and 

 also, if possible, to determine the physiological effect of compounds 

 that may be identical in rancid fats, is under waj-. Considerable 

 progress has been made but it is too earh^ to announce results. 



DIPS AND DISINFECTANTS. 



The laboratory of dips and disinfectants received and examined 

 112 samples of clips, disinfectants, and related materials. 



During the calendar year 1921 there were sent out to inspectors 

 in the field 1,009 new test outfits for arsenical dips and supplies 

 sufficient to make 471,840 field tests for arsenic; 67 new test outfits 

 for lime-sulphur dips and sufficient supplies to make 16,000 tests; 

 and 21 new outfits for testing nicotin dips and supplies sufficient to 

 make 5,580 tests. There were thus sent out a total of 1.097 new test 

 outfits and supplies to make a total of 493,420 field tests. 



Work has been continued on the general subject of the mode of 

 action of phenolic disinfectants, with special attention to the funda- 

 mental question of why the phenols differ so markedly in germicidal 

 activity. After obtaining with some difficulty a sufficient number 

 of pure phenols, and then making an exhaustive comparative study 

 of their physical and chemical properties and correlating the ob- 

 served differences with the differences in their germicidal activities 

 reported by bacteriologists, the conclusion was readied that the dif- 

 ferences in killing power manifested by different phenols are ap- 

 parently due to physical differences and are not directly a conse- 

 quence of any difference in chemical action. 



The phenol investigations have led to a study of colloidal phenom- 

 ena and principles. It is believed that new relationships have been 

 discovered and certain important principles formulated which will 

 be of* great assistance in correlating and explaining the generally 

 obscure phenomena of suspensions, emulsions, and colloids. 



TUBERCULIN AND MALLEIN. 



The demand for subcutaneous tuberculin has continued to de- 

 crease, while there has been a marked increase in the requests for 

 ophthalmic and intradermic tuberculin. The year's output, which 

 was supplied mostly to bureau inspectors but partly also to State 

 and local officials, was as follows : Subcutaneous tuberculin. 2,477,224 

 cubic centimeters, a decline of 42 per cent from the preceding year; 

 ophthalmic tuberculin, 1,577,880 disks, an increase of more than 

 190 per cent; intradermic tuberculin, 1,026,745 cubic centimeters, 

 sufficient to make 5,133,725 tests. The newly installed apparatus 



