260 



Studies in the Hi/brid Bistoninae. Ill 



been reared with elaborate care, during the same season, and under 

 conditions likely to eliminate phenotypic variation in all its phases, for 

 another purpose, it was perceived that, as the phylogenetic divergence 

 of the second species in any particular cross from hirtaria increased, 

 there was a concomitant and proportional increase in the physiological 

 robustness of the hybrid organism which, in its iturn, entailed : 



(1) A size increased beyond the theoretical expectation. 



(2) An acceleration in the speed of feeding up. of the larvae. 



(3) Great disease resisting powers. 



(4) An enormous reduction of the time of lying over indulged in 

 by some of the species and which, presumably, should have affected any 

 hybrid in which that species took part. 



Nyssia graecaria 



Nyssia 



PoecMopsis rachelae 



Poecilopsls Isabel lae 



Poecflopsis 



PoecUopsis 

 Lycia ursaria Lycia hirtaria 



zonaria 



lapponaria 



pomonaria 



