Toya.na, Mendel'* laws of heredity as applied to the silk-wo'rm crosses. 



329 



the crosses between "striped whites" and "no-marking yellows 

 we havc produced two new breeds quite different from the pa- 

 rents, viz "striped yellow" and "no-marking white". 



As we see, the results obtained with these crosses afford an 

 excellent illustration for Mendel's principle oi' dihybrids and will 

 serve as a verification of bis law. 



B. Modified cases of dihybrids. 



This series of experiments gives us very interesting combi- 

 nations and segregations of parent-characters in the offsprmg. As 

 far as I am aware, such cases seem to have been never observed. 



Breeds chosen for the crossing are 1. "Japanese normal mar- 

 king whites" and 2. "Siamese striped whites" before mentioned. 

 Both are, however, not pure breeds, sometimes they produce no- 

 marking worms. Tims we must consider them to be cross-bred 



forins. 



The first cross generation. 



The reciprocal crosses gave at first three kinds of offsprings. 



Of 10 parents . 



A. 4 parents produced uniform offspring consisting of striped 

 white worms only» 



B. 3 parents produced mixed offspring, consisting of 



rstriped whites 482 — 47,11 °/ o; 



'Japanese normal markings . . 541 = 52,88 °/ , 

 [ i. e. approximately 1:1. 



C. 3 parents produced mixed offspring, consisting of 



striped whites 352 = 4N,21 °/ , 



Japanese normal markings . . 196 = 26,84 "/„, 



no marking ones 182 = 24,93 °/,„ 



i. c. approximately 2:1 : 1. 



The second generation. 



In this generation, we kept for experiments only those which 



produced in the last generation simply striped whites. Each of 



these parents mated with similars gave three kinds of worms. 



striped, normals and no-marking ones in the average proportion of 



striped whites 2300 or 74,75 °/ , 



Japanese normal marking ones . . 597 ,, 18,86 °/ , 

 no-marking whites . . , 202 „ 6,28°/ , 



that is to say, striped whites 12, Japanese normals 3, no-marking 

 whites 1. 



The third generation. 

 In this generation, we again kept only "striped whites" for 

 experiments. They produced the following four kinds of offsprings: 

 A. Mixed offspring of "striped whites" (102 = 74,9%), and 

 Japanese normal marking ones (34 = 25°/ ). 



