Experiments with Snails, Moths, and Beetles 153 



(345) are produced in the proportion of 3 : i. In two cases, how- 

 ever, all the offspring (265 in one case, 182 in the other) were 

 spotted. If these are paired, they produce only spotted forms. 

 Clearly we have to deal here with extracted dominants. 



The results may be briefly summed up as follows : the two 

 types of beetle show alternate dominance and recession, the 

 spotted character being dominant, the black being recessive. 

 By isolation both types may be obtained "pure." In nature 

 both are continually crossing and recrossing, so that the chances 

 are that most individuals are impure, but by selection pure 

 breeds can be quickly obtained from them. 



Experiments with the Currant Moth 



There is a curious case, reported by Raynor and Doncaster 

 for the currant moth (Abraxas grassulariata) , in which there is 

 a rare variety, A. lacticolor, that had previously been found only 

 in the female sex. The variety is recessive in the first generation 

 when crossed with the parent form. The offspring, however 

 (i^i), produce males, all of which are the ordinary variety grassu- 

 lariata, and females, half of which are like the males and the 

 other half are var. lacticolor. When, however, a lacticolor fe- 

 male is paired with a {F-^ male hybrid (L ? x G (L) $), some of 

 the male offspring are lacticolor (and others female). The ex- 

 planation of the transference to the male of the female character 

 is not apparent. 



Experiments with Tephrosia 



A series of hybridizing experiments between the moths 

 Tephrosia bistortata and Tephrosia crepuscularia have been 

 described by Tutt (based on records by Riding and Bacot). 

 These two species are sufficiently similar to have been put to- 

 gether as one by some entomologists because occasionally indi- 

 viduals have been found that could not be referred with cer- 

 tainty to either species, but Tutt describes a number of constant 

 differences between the two forms and regards them as distinct. 

 Both species have a melanitic variation, that of T. bistortata 



