104 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



manuscripts were prepared for outside publication in scientific, agri- 

 cultural, and other journals. In addition the bureau furnished to 

 the press service of the department 270 articles and items for general 

 publicity. 



A series of 10 pictures, of a size suitable for mounting and display, 

 illustrating various species of farm animals of good quality, has been 

 completed. The subjects include dairy and beef cattle, horses, mules, 

 swine, sheep, goats, and poultry. These pictures are intended to show 

 desirable types of livestock in the interests of the campaign for im- 

 proved breeding. 



In cooperation with the department's Office of Exhibits the bureau 

 designed and aided in preparing exhibits for numerous agricultural 

 expositions, fairs, and shows. Special exhibits for the National Dairy 

 Show and the International Live Stock Exposition attracted much 

 attention and favorable comment. 



Among new motion pictures prepared during the year in collabora- 

 tion with the department's motion-picture laboratory was one en- 

 titled " Exit Ascaris," depicting in story form the life history of the 

 roundworm of swine and methods of prevention. An earlier film, 

 " Great Dairy Sires and Their Daughters," has proved to be among 

 the most popular in the department's collection. The film on tuber- 

 culosis eradication has been a valuable aid in advancing that work. 



REPORTS BY DIVISIONS. 



The year's work as conducted by the various divisions of the bureau 

 is presented more fully in the following pages. 



ANIMAL HUSBANDRY DIVISION. 



The work of the Animal Husbandry Division, consisting chiefly of 

 research in animal and poultry husbandry, was conducted under the 

 direction of George M. Eommel, chief, up to the end of October, 

 1921, when his resignation became effective. For the remainder of 

 the fiscal year the activities of the division were in charge of E. W. 

 Sheets, acting chief. 



ANIMAL HUSBANDRY EXPERIMENT FARM. 



Numerous improvements were made at the Animal Husbandry 

 Division Experiment Farm, Beltsville, Md. The numbers of live 

 animals remain about the same as in the preceding year. The farm 

 is used as a practical laboratory and proving ground for solving 

 livestock problems. 



ANIMAL GENETICS. 



The principal project in animal genetics has been the study of 

 the effects of inbreeding and crossbreeding, using guinea pigs as 

 material. Clear-cut results have been obtained and are presented in 

 three papers, which are in press in two department bulletins. 



The study of the theoretical effects of various systems of mating 

 has been continued. A paper is in press describing a method of 

 obtaining a coefficient of inbreeding which is applicable to complex 

 pedigree and which gives an exact measure of the effects to be ex- 

 pected on the Mendelian theory of inbreeding. 



