MAINE AGRICULTURAL EXPERIMENT STATION. 9 



deals with the results which may theoretically be expected to 

 follow the continued mating of first cousins of different types, 

 and also continued mating of the type uncle x niece. The 

 second' has to do with a system of recording types of pedi- 

 grees in experimental or other breeding operations. This will 

 chiefly be of use to those who are keeping precise records and 

 breeding more or less along experimental lines. There has 

 also been prepared a bulletin on the general subject, which is 

 now in press'. 



With the very efficient aid of Mr. S. W. Patterson the study 

 of inbreeding in Jersey cattle has been brought to completion 

 and the results are now being prepared for the press. They 

 give us for the first time a definite, comprehensive, and quanti- 

 tative idea of the average degree of inbreeding prevailing in a 

 race or breed of domesticated animals, at a particular time in 

 the history of that breed. Because of the novelty and general 

 interest of these results certain of them are here reproduced 

 in Table 5 and Figs. 1-4 inclusive. The derivation and signifi- 

 cance of coefficients of inbreeding have been explained in 

 earlier publications" and need not be repeated here. For rea- 

 sons which cannot be gone into here, but will be in the detailed 

 publications, it is impossible in the case of cattle to arrive at 

 an absolutely exact value of the mean inbreeding coefficients. 

 What we can do is to determine upper and lower limiting 

 values, between which the true, and undeterminable value lies. 

 Such upper and lower limiting values are presented in Table 5. 

 Recalling that the higher the value of a coefficient of inbreed- 

 ing the more intensely the animal is inbred, we may turn our 

 attention to Table 5 and the diagrams. 



^Pearl, R. A System of Recording Types of Mating in Experimental 

 Breeding Operations. Science, N. S., Vol. XLII, pp. 383-386, 1915. 



'Pearl, R. Further Data . on the Measurement of Inbreeding. Me. 

 Agr. Expt. Stat. Bull. 243, 191 5. 



^Cf. for example, Pearl, R. The Measurement of the Intensity ot 

 Inbreeding. Me. Agr. Expt. Stat. Bull. 215, 1913. 



