SEX DETERMINATION IN CATTLE. 2IJ 



based his conclusions on 29 experiments with cows, in which 

 union took place at the beginning or at the end of the period of 

 heat. Others have failed to confirm his conclusions, and con- 

 tradictory results have been obtained with rabbits, and hens." 

 Neither Marshall nor Morgan give any detailed references to 

 the literature. 



F. R. Marshall 1 evidently has Thury's theory in mind in the 

 following statement but has apparently received the tradition 

 in slightly garbled form: "The commonest idea about sex deter- 

 mination is that females bred at the beginning of the period of 

 heat produce male offspring. Other notions are based on the 

 same supposed principle, namely, that an ovum fertilized while 

 immature produces a male; maturity is supposed to be in pro- 

 portion to the age of the ovum and the nutritive condition of the 

 dam." He then proceeds (on grounds it must be said which 

 are strictly a priori) to demolish all such notions. 



So far as we have been able to discover the following are the 

 only experimental tests which have ever been accorded Thury's 

 theory as regards cattle breeding, which at all adequately fulfill 

 the conditions necessary for a critical test. Supposed tests of 

 the theory carried out with plants, multiparous mammals, 

 birds, etc., will not be discussed here, because it seems to us either 

 (a) obvious a priori that the theory could not possibly apply, in 

 the nature of the case, to some of the organisms and forms of 

 reproduction which Thury and subsequent workers attempted 

 to include in its purview, or (b) that the so-called tests of the 

 theory were in many instances absolutely uncritical and could 

 not have been expected under the most favorable circumstances 

 to have yielded any really significant results one way or the 

 other. The tests with cattle, which if carefully carried out must 

 yield critical evidence, are, as has been said, meager enough in 

 number and magnitude. The first were made shortly after the 

 publication of the theory at the agricultural academies at Proskau 

 and Eldena. 2 The results were as follows: 



1 Marshall, F. R., " Breeding Farm Animals," Chicago, 1911. 



2 Annalen der Landwirlschaft, Jahrg. 23, Bd. 46, p. 271, 1865. For the facts 

 regarding the.se and the following tests we are indebted to Diising's (loc. til.) 

 memoir. 



