BUREAU OF ANIMAL INDUSTRY. 247 



by the various tissues of cattle dipped in arsenical solutions, such as 

 are at present in use for combating the Texas fever cattle tick. Ex- 

 periments intended to obtain the desired information are already 

 under way, the work being carried out in collaboration with the Zoo- 

 logical Division. 



During the year there was developed a method for the determina- 

 tion of nicotin in nicotin solutions and tobacco extracts, which seems 

 to ofi'er decided advantages over methods previously available. An 

 account of this work and a description of the method have been pub- 

 lished as Bureau of Animal Industry Bulletin 133. 



For more than two years dimethyl sulphate has been employed in 

 this laboratory as a reagent for testing creosote oils and dips prepared 

 therefrom. The test has proved of such value that a description of 

 it has been published as Bureau of Animal Industry Circular 107. 



An investigation into the effect upon the composition of coal-tar 

 creosote baths caused by the passage of sheep through such baths has 

 been continued from the previous year. It was proved that as 

 di[)ping is continued the percentage of cresylic acid contained in such 

 baths becomes progressively less. It is probable, therefore, that as 

 sheep pass through such baths their wool to a certain extent plays the 

 part of a strainer and mechanically remove from the emulsion an 

 undue proportion of globules of oil and cresylic acid. 



Examination of samples of dips, disinfectants, and related materials 

 submitted by manufacturers, bureau inspectors, the general supply 

 committeee for the Executive Departments and by other Government 

 offices, has been continued as in the past with no new developments 

 worthy of note. 



Through General Order 143 the Secretary of Agriculture created 

 the Insecticide and Fungicide Board to assist him in the enforcement 

 of the insecticide act of 1910. The chief of the Biochemic Division 

 was made chairman of the board, and the Secretary directed that a 

 certain part of the work which naturally fell within the province of 

 the Bureau of Animal Industry should be carried out by this bureau. 

 The laboratory work, w^hich has necessitated the assignment of two 

 bureau employees to this work exclusively, has so far consisted in 

 the examination of certain classes of samples. 



TUBERCULIN AND MALLEIN. 



The amount of tuberculin furnished to State, county, and municipal 

 officials in various States and Territories for diagnosing tuberculosis 

 in cattle continues to increase. During the past year there was dis- 

 tributed a total of 422,043 doses, this being an increase of approxi- 

 mately 20 per cent over the previous fiscal 3^ear. 



As all officials who receive tuberculin from this bureau are required 

 to report the results of the tests made by them, a large number of 

 records have collected during the years that tuberculin has been 

 distributed. During the past year it has been possible to go over a 



fortion of these records, and some interesting data have been secured, 

 t is evident that in determming the reliability of the tuberculin it is 

 possible to utilize only such records as show the results of autopsy 

 on the tested animals. Excluding all tests which were defective in 

 any respect, we have been able to secure temperature charts of 8,980 

 tuberculin tests on cattle that were afterwards slauglitcrcd. In 

 going over these charts the tuberculin reaction has been regarded as 



