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WILLIAM LAWRENCE TOWER. 



mid types, that is, they were "heterozygous" in their nature and 

 every one of them gave, when inbred, the following behavior in 

 the Fg generation : the larvae in the first stage were all alike, in the 

 second stage they were clearly divisible into two types, white and 

 yellow in a proportion of approximately 1 : 1 ; in the third stage 

 the larvae of all the mid types divided into four classes: white 

 without spots (Whs), white with spots (WhS), yellow without 

 spots (YIS), and yellow with spots (Yls) ; and each of these 

 classes gave three classes of adults, that is, from the white larvae 

 without spots came forms which were exactly like the female 

 parent, forms exactly like the male parent, and an intermediate 

 type. The same classes of adults came from the white larvae 

 without spots, from the white larvae with spots, from the yellow 

 larvae with spots and the yellow larvs without spots, giving thus 

 twelve sharply marked categories of adults in the second hybrid 

 generation, each having a definite type of behavior and carrying 

 presumably a definite gametic constitution, the product of its 

 past experience. The census of larval characters from nine mat- 

 ings was as follows : 



■ From these larvae there came the three types: signaticollis 

 (sig.), mid (mid), and undecimlineata (ii-lin.) as follows: 



lA hybrid sport 9 with the elytral stripes double — because the ancestor of 

 a stable race. 



