Toyama, Mendel'« laws of heredity as applied to the silk-worm croases. ;;;-;| 



3. S X C = seemingly striped forms alone. 



4. (g + N ) (C + N). " In this cross, we take for granted that 

 both characters in parentheses sometimes behave as a whole 

 character, sometimes as separate characters. In the former case, 

 the resnlt wonld be (C + N) + (S + N) = (C + N + S), so that 

 one dominant character or striped character will appear as an 

 active component, which necessarily resnlts in the uniform striped 

 offspring. In the latter case, i. e. (C + N) (S + N) = CS + SN 

 _|_CN + NN, two, striped worms (50°/ ), one "normal" (25°/ ) and 

 one no-marking one (25°/ ) will be the resnlt, 



Thus, from this crossing we may expect to get the following 

 offspring: 



1. uniform striped offspring. 



2. mixed offspring consisting of striped and "normals" in the 

 proportion of 1:1. 



3. A mixture consisting of two striped worms (50°/ )j one " nor - 

 mal" (25°/ ) and one no-marking worms (25°/ ). We wil1 

 see that these figures agree fairly well with those actually 

 obtained. 



In the second generation, when the striped offspring (Nr. 1 ) 

 are mated together, we may develop the following formulae: 

 (C + N) + (S + N) X (C + N) + (S + N) = (C 2 + 2CN + N 2 ) 

 X (S 2 + 2 SN + N 2 ) = CS 2 + 2 CNS 2 + N 2 S 2 + 2CNS 3 + 4CN 2 S 

 _^_ 2 SN 3 + CN 2 + 2 cCN 3 -f- N 4 = 1 2 stripes + 2 "normals" + 1 no 

 marking from which we estimate that 



striped worms I2 / ]6 or 75°/ , 



uormal worms 3 /i<; or 18>75°/ , 



no-marking worms 1 ha 0T G/-5 / - 



This illustrates clearly the phenomena actually obtained in the 

 second generation. 



Similar reasoning will serve to illustrate the behavior of the 



posterity of these crosses. 



* * 



* 



The facts and considerations above referred to may furnish 

 a further proof for the verification of the Mendelian principles and 

 lead us to conclude that Mendel's laws may be applied, with eqnal 

 exaetness, to plants as well as animals. 



IV. 



Forms of cocoons. 



In the crosses between Siamese (cocoons, spinale in shape, 

 pointed at one or both ends, without constriction in the middle, 

 with much floss) and Japanese (cocoons, cylindrical or oblong in 

 shape, with rounded ends, and with a constriction in the middle, 



