428 GENETICS: W, E. CASTLE 
INHERITANCE OF QUANTITY AND QUALITY OF MILK 
PRODUCTION IN DAIRY CATTLE 
By W. E. Castle 
BussEY Institution for Research in Applied Biology, Forest Hills, Mass. 
Communicated, August 1, 1919 
In 1911 the late T. J. Bowlker undertook at his farm in Framingham, 
Mass., an experimental study of inheritance in dairy cattle by the mod- 
ern method of crossing pure breeds and looking for a recombination in 
the second crossbred generation of the characters differentiating the 
breeds crossed. The breeds which he selected for study were the Hol- 
stein-Friesian and the Guernsey, one supreme among dairy breeds in 
quantity production, the other of very high rank as regards quality of 
milk produced. It was his belief that if quantity and quality of milk 
production were independently inherited characters, it should be pos- 
sible to combine them in a single race by the method of crossbreeding, in 
accordance with MendeFs law. The desired recombination of qualities, 
if attainable, would be of much importance to the dairy industry, and at 
any rate the knowledge whether such recombination is attainable would 
be a valuable contribution to science. With rare insight into the dif- 
ficulties surrounding the problem and the proper method of attacking 
it, Mr. Bowlker planned his experiment on a considerable scale. He 
had a herd of some 40 pure-bred registered cows, about two-thirds of them 
being Holsteins, the rest being Guernseys. He also had a pure-bred 
registered bull of each breed, and in the pedigrees of these bulls excellent 
blood-lines were represented. He decided to cross-breed the entire herd, 
mating the Holstein cows to the Guernsey bull and the Guernsey cows 
to the Holstein bull. In this way what are knovm as reciprocal crosses 
were made between the two breeds. In all about 140 Fi calves were 
produced between the years 1912 and 1919. As last as the Fi heifers 
attained suitable age they were bred to Fi bulls in order to secure the 
desired F2 generation, in which combination of characters might be 
expected. About 35 living F2 calves have been produced in this way of 
which the heifers have been saved for milking tests, for which, however, 
they are still too young. 
Mr. Bowlker did not Hve to see the completion of his experiment but 
died in February, 1917. His family undertook to complete the unfin- 
ished work, with such scientific advice as I could give them, but practical 
difficulties having arisen which make it impossible to carry the work 
