234 GENETIC STUDIES ON THE SILKWORM 
P65'i4 
92 
213 
1 
: 2. s 
P6/14 
3i 
325 
1 
: 10. ; 
P68'i4 
44 
357 
1 
: 8.1 
4-moulters x 
4-moultei 
'S. 
A 1 14M5 
212 
230 
1 
: 1.1 
A 128'is 
131 
107 
1.2 
: 1 
A i2(/i5 
93 
93 
1 
: 1 
A ? 1 1 ' 1 c 
83 
92 
T 
1 
• TT 
1.1 
A 2I2'l5 
205 
174 
1.2 
: 1 
A 2 4 5'i5 
234 
187 
i-3 
1 
A 246^5 
217 
241 
I 
: i.l 
A 279' 1 5 
152 
150 
I 
: 1 
To what extent the above cases owe their abnormal phenotypic ratios to 
intransmissible fluctuation, and to what extent owe to the genetic cause, is a 
difficult question to solve. The multiple factor theory is applicable to the 
question only when some of these cases, at least, have been proved to be 
neither due to fluctuation, nor accidental, but due to genetic recombination. 
Many of these abnormal cases, if not all, can be interpreted, for instance, on 
the assumption that either 3- or 4-moulting arises according as two con- 
ditional factors, x a and x b , are present simultaneously or not. Some such 
hypothesis assuming the presence of more than one allelomorphs in the inherit- 
ance of moulting character appears to me at present to be the most plausible. 
4) Multiple Factors Concerning Colour and Other Cocoon 
Characters. 
The silkworm cocoons may be divided into two distinct groups, coloured 
and colourless. The colourless or white cocoons are further subdivided into 
dominant and recessive whites (ToYAMA 191 2 a, Tanaka 1913 a). Two subdi- 
visions are recognized also in the coloured cocoons, namely the yellow and 
green. The "green" colour of the cocoon might rather be classed in the yellow 
series according to the general nomenclature of colours, yet the yellow-cocoon 
