326 Tuvnnm. Mendel's laws of heredity as applied to tho silk-worm crosses. 



yellow form mated with similars will produce (D -\- R) (D -|- R) 

 = white 25°/ and yellow 75°/ j "with whieh the actual figures ob- 

 tained agree fairly well. 



On the contrary, when we cross them with pure yellow form 

 or D, the following corabinations may be expected in the first 

 crosses. 1, (D-f-R)D; 2, D X D. Both are dominant forms. In 

 the second generation paired with similars, (D -\- R) 2 , (D -J- R) D 

 and D X D will be produced, in which the latter two (D -j- R) D 

 and DXD will exhibit dominant character. So, if we rear only 

 a portion of the offspring, it might oeeur not improbably that only 

 these latter combinations are kept for experiments and in this case 

 the offspring will obviously again display the dominant character 

 in the second generation. Our results are possibly due to such 

 cause. 



The general conclusion to be drawn froni all above given is 

 that the colour characters of the cocoon of the silk-worm strictly 

 follow the Mendel's law. 



II. 

 The yarious larval markings. 



Results closely similar to those above stated with the colonrs 

 of cocoons were obtained with various larval markings of the silk- 

 worms when we crossed different breeds having particular larval 

 markings. 



The breeds chosen for the experiment are 1. "pale whites" 

 characterized by the absence of markings of any kind except on 

 the dorsal surface of the first and second Segments where their 

 faintest trace may be detected, 2. "striped whites" which are cha- 

 racterized by the possession of dark striped markings on each 

 intersegmental region from the third to the last segment, Besides 

 these there are the normal markings on the dorsal part of the 

 first and second segments, while those semilunar markings which 

 are common on the dorsal part of the eighth segment of the normal 

 breed are wanting. 



The former breed remains constant, while the latter often 

 produces some pale white worms and so is to be considered as a 

 cross-bred form between the "pale white" and the "striped white" 

 breeds. 



The first generation of the reciprocal crosses between these 

 two breeds gave rise to two kinds of offspring, one consisting 

 simply of striped individuals, another consisting of striped as well 

 as pale white (striped worms 528 and pale white worms 528 that is 

 to say, approximately in the proportion of 1 : 1). 



In the subsequent generations, the pale white forms which 

 have appeared in the first cross remain constant, breeding true to 



