YOSHIMARO TAN AK A 335 
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spinner is yellow-blooded and hence yellow-legged, in contrast to the green- 
cocoon spinner in which the haemolymph and the abdominal legs are never 
yellow. Consequently these two strains are readily distinguishable, already 
in the larval stage, whereas it is by no means easy to distinguish the green 
and white before spinning. 
The yellow character is dominant over the green, but the dominance is 
not complete, the cocoons of YG individuals being intermediate of those of 
YY and GG parents in colour, on account of the simultaneous development of 
the two colours. 
Not only in my previous papers, but also in the preceding pages of the 
present communication, I have, for the sake of simplicity, dealt with the 
yellow as a simple character. Various sorts of colour subtypes can, however, 
be recognized in the yellow as well as in the green series : to speak more 
fully, orange n , cadmium yellow, chrome yellow, salmon, salmon-buff, cream 
and many intermediate colour subtypes are involved in the yellow type ; 
while citron yellow, sulphur yellow, primrose yellow, greenish white, and 
many intergrades belong to the green series. The majority of these colour 
races transmit their characteristics, as is learned by my unpublished experi- 
ments ; they are therefore undoubtedly dependent upon respectively different 
factors. 
The inter-crossing of different subtypes often gives monohybrid F., ratio, 
whereas in some other cases, it gives rise to a widely ranging variability in 
the cocoon colour, a "breaking up" being brought about. This is a fact 
which speak for the existence of several allelomorphs for the yellow and green 
colours. More detailed account on the inheritance of yellow and green 
characters will appear on a future occasion. 
There are some reasons to believe that the multiple factor hypothesis 
fits in best for the inheritance of shape and size of cocoons, thickness and 
length of cocoon-fibres ("baves") and other quantitative characters in the silk- 
worm. My experiments in this direction is now in progress. 
1) According to the nomenclature of colours by Ridgway (1886). 
