38o EXPERIMENTAL STUDY OF INHERITANCE 



cow and red bull may have the unpopular red-and-white 

 calves. 



Mr. Duthie of Collynie has told us of the following case : — 

 A light roan cow of very good quality was served repeatedly 

 by a crack light roan buU. She had three or four very good 

 white calves. But a roan calf was much desired, and the follow- 

 ing experiment was tried. She was served by the roan bull, 

 and at the same time she had in view — over the wall — a red 

 yearHng, which was afterwards put into the next stall. The 

 cow eventually gave birth to a red roan heifer calf of great 

 beauty. This is not an isolated case. From a pure white bull 

 and a white cow a fine red roan calf was produced, and this 

 was attributed to the fact that the white cow was continually 

 accompanied by a red cow ! 



It often happens that the crossing of a white bull and a red 

 cow yields a roan, and it sometimes happens that when this roan 

 is served by a roan bull, the result is a white calf. If this sort 

 of experiment were followed up, it might be found that Mendelian 

 phenomena occur. 



§ 7. Other Experiments on Heredity 



Our survey of cases must be supplemented by reference to 

 the works of Bateson, T. H. Morgan, De Vries, and others ; 

 but we have said enough to show,— (i) that Mendelian 

 phenomena are well illustrated in certain cases — e.g. peas, 

 mice, rabbits, poultry, snails ; (2) that in other cases, while 

 there are clear Mendelian phenomena according to some ob- 

 servers, discrepant results have been reached by others — e.g. 

 silkmoths ; (3) tha in other cases, while there are hints of 

 Mendelian phenomena, the results cannot be r.terpreted in 

 conformity with Mendelism without far-fetched ingenuity — e.g. 

 pigeons ; and (4) that in other cases the results of hybridising 

 do not at all agree with Mendel's Law — e.g. in sheep and man. 



