150 Experimental Zoology 
white cocoons, are crossed, the offspring (F',) produce only yel- 
low cocoons. When these hybrids are inbred they give two 
kind of individuals; namely, those producing white and those 
producing yellow cocoons in the proportion of 25.03 per cent 
whites to 74.96 per cent yellows. The whites are extracted re- 
cessives, and are found to breed true. The yellows are of two 
kinds, one kind giving only yellow-producing offspring (the ex- 
tracted dominants) and the other kind producing yellow as well 
as white in the proportion of 3 to 1 (the dominant reces- 
sives). A more complex result was obtained when Japanese 
‘whites’? and Siamese “yellows”? or when Japanese ‘“ whites” 
and European “‘yellows” are paired. The first generation give 
offspring that produce yellow cocoons. When these indi- 
viduals are paired, they give in the second generation four 
kinds of cocoons: (1) pure yellow, 70 cases; (2) pale pinkish 
yellow, 21 cases; (3) greenish white, 24 cases; and (4) pure 
white, 12 cases. 
The results show apparently that we have to do here with three 
characters, one of the races used being a monohybrid and the 
other a dihybrid. In subsequent generations the pure white 
type breeds true. Some of the yellows give only yellows; others 
give white (25 per cent) and yellow (75 per cent); others give 
yellow (75 per cent), flesh-colored (25 per cent), and still others 
white and greenish white (25 per cent), yellow (56 per cent), and 
flesh-colored (19 per cent). 
The flesh-colored forms of the second generation gave white 
(25 per cent) and flesh-colored (75 per cent). The greenish 
white type of the same generation gave white and greenish white 
offspring. 
Toyama used two breeds of caterpillars, pale whites character- 
ized by the absence of markings, and striped whites having dark 
stripes. The former breeds true, while the latter produces some 
pale whites and is therefore a cross breed form. The hybrids 
produced by uniting these breeds were white and striped worms 
in equal numbers. In subsequent generations the whites re- 
mained true while the striped kind gave both whites and striped. 
