38 INHERITANCE IN SILKWORMS^ I 



were of Japanese White race type, as were also all the cocoons spun by 

 these larvse. 



In 1906 several double matings were made but in a different way. 

 The female was not allowed to lay eggs after the first mating but was 

 immediately, after the first mating, remated with a male of different 

 race, then allowed to lay all of her eggs, and the offspring got in 1907 

 from these double matings all reared through to maturity, and their 

 characters, larval and pupal, noted and tabulated. The matings and 

 results were as follows: 



(No, III.) Female Bagdad (white larva, white cocoon) was 

 mated with a male Bagdad and then with a male Istrian (buffy larva, 

 golden yellow cocoon). Result, all the young were of Istrian larval 

 type and of Bagdad cocoon type. Too much stress cannot be laid upon 

 the larval type because the Bagdad and Istrian larvse are much alike, 

 although the noticeable clayey or buffy tinge of the Istrian larvae is 

 really a fairly distinguishing character. 



(No. 112.) Female Bagdad mated with male Bagdad and then 

 with male Istrian. Result, eggs all sterile ; no hatches. 



(No. 113.) Female of Italian Salmon (white larva, pink yellow 

 cocoon) mated with male of same race and then with male Bagdad 

 (white larva, white cocoon.) Result, all white, i. e., Bagdad cocoons. 



(No. 236.) Female of Japanese Green race (white larva, green 

 cocoon) mated with male Bagdad (white larva, white cocoon) for 

 i^ hrs., then with male Istrian (clayey-white larva, golden-yellow 

 cocoon) for a longer time. Result, all golden-yellow, i. e., Istrian 

 cocoons. 



(No. 238.) Female of Bagdad race (white larva, white cocoon) 

 mated with male Istrian (clayey- white larva, golden-yellow cocoon) 

 for 13^ hrs. and then with male Japanese Green (white larva, green 

 cocoon) for a longer time. Result, cocoons all golden yellow, i, e,, 

 Istrian. 



(No, 239.) Female of Bagdad race (white larva, white cocoon) 

 mated with male Japanese Green for i^ hrs., then with male Istrian 

 (clayey-white larva, golden-yellow cocoon) for a longer time. Result, 

 all cocoons golden-yellow, i. e., Istrian. 



These few experiments (the subject is being followed up more 

 extensively this year) show that in such double matings one strain is 

 potent over another. With two kinds of spermatozoa in the sperma- 

 theca, fertilization of the eggs does not occur according to the laws of 

 probability, but the spermatozoa of one strain are successful in the race 



