CONFIRMATIONS OF MENDEL S LAWS 361 



answer, nor is the answer the same as that once given by Job " 

 (R. C. Punnett, 1905, p. 18). 



Silkworms. — Toyama paired Siamese silkmoths, with yellow 

 or with white cocoons; the offspring produced only yellow 

 cocoons. When the hybrids were inbred, the result was two 

 sets, one producing white cocoons, the other producing yellow 

 cocoons, and the proportion was Mendelian — 25*037 white and 

 74-96 yellow. The whites bred true ; the yellows when inbred 

 showed themselves to be pure dominants or " yellows " and 

 dominant- recessives — i.e. splitting up again into yellows and 

 whites in the usual proportion. More intricate experiments 

 confirmed this general result. 



It must be noted, however, that Coutagne has made much 

 more elaborate experiments with different results, which in many 

 cases cannot be interpreted on the Mendelian theory. Thus he 

 found (i) that the hybrid forms were sometimes blends of 

 the parents and different from both; (2) that in other cases 

 the brood included some like one parent in a particular 

 character, some like the other parent, and some intermediate ; 

 and (3) that in other cases the individuals showed no fusion 

 of characters, but resembled one or other parent. It is likely 

 that the discrepancy may be explained as due to considerable 

 diversity of origin in the domesticated races of silkworm, so 

 that, while they breed true when left to themselves, a dis- 

 turbance of the usual routine leads to the liberation of latent 

 characters. 



Lina lapponica. — Miss McCracken has made a fine study of 

 the hereditary relations in this Californian beetle, which occurs 

 in two types, spotted (dominant) and black (recessive). They 

 are always crossing in natural conditions, but there are no 

 intermediates, and it is easy by isolation to rear a" pure " spotted 

 race and a " pure " black race. When spotted forms are paired 

 they may produce only spotted progeny — a case of extracted 

 dominants. In other cases, however, they yield spotted and 



