74 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



times sheep, and in one instance a colt, and has also appeared in lo- 

 calities remote from trading centers. 



The bureau has given special attention to the study of this disease 

 and is continuing these investigations. Medicinal treatment is of 

 little value because of the acute and rapidly fatal character of the 

 malady. Resort must be had to preventive measures. Good results 

 have followed preventive treatment with bacterins according to the 

 method of Mohler and Eichhorn of this bureau. Plenty of good 

 water, good feed, and good care during shipping and yarding tend 

 to prevent and reduce the losses. Further details of the work regard- 

 ing this disease are given in the portion of this report relating to the 

 Pathological Division. 



PUBLICATIONS. 



Fifty-four new publications, comprising 1,006 printed pages, were 

 issued or contributed by the bureau during the fiscal year. These 

 included 8 Farmers' Bulletins, 7 department bulletins, 7 articles in 

 the Journal of Agriculture Research, 5 articles for the Department 

 Yearbook, 13 issues of Service and Regulatory Announcements, and 

 13 miscellaneous pamphlets. Numerous articles were also furnished 

 for the Weekly News Letter, and several papers were contributed 

 to outside scientific and technical journals. In addition 60 orders 

 in the nature of regulations were issued. By special resolutions of 

 Congress the books on Diseases of the Horse and Diseases of Cattle 

 were revised and submitted for printing, for distribution by Senators 

 and Representatives. 



ANIMAL HUSBANDRY DIVISION. 



George M. Rommel, Chief. 



ANIMAL GENETICS. 



The experiments on inbreeding in guinea pigs have been continued. 

 At present there are 17 families in existence which trace back by ex- 

 clusively brother-sister matings to 17 original pairs. Some of these 

 have reached the sixteenth generation of inbreeding. One family has 

 become extinct since last year. Another was disposed of owing to 

 descent of all living lines from a mating of very doubtful character. 

 The past winter was disastrous to this work. Many matings were 

 lost, and only a very small percentage of the young born were raised. 

 Several families were seriously cut down in size. Most of the stock, 

 however, is recovering rapidly. 



The principal new feature of the experiments is extensive cross- 

 breeding between members of different highly inbred families, par- 

 ticularly between families which are in a feeble condition or in which 

 certain opposite characters have become fixed. 



Among the controls, important relations have been found with re- 

 spect to sex ratio, size of litter, interval between litters, gestation 

 period, birth weight and early growth, early death rate, and effects 

 of time of year, of age and condition of mother, and of birth rank. 

 These results are being compared detail for detail with conditions in 

 the different inbred families. The modes of inheritance of certain 

 special traits, such as white and yellow spotting, dilution of color, 



