LÉPIDOPTÉROLOGIE COMPARÉE 477 



2. We can hâve a différence between the state of the chro- 

 mosomes of maie producing spermatozoa and that in female 

 producing spermatozoa. just as has been definitely observed in 

 other insects {Protenor belfragi) ; this condition may vary in the 

 two groups considered and thus, on crossing give rise to the phe- 

 nomena observed. 



In the first case, the condition assumed is mechanical, and is 

 that, whereas spermatozoa bearing male-ness are small and 

 capable of penetrating the micropyle of the ova, on the contrary, 

 spermatozoa carrying female-ness are large, and therefore unable 

 to penetrate an ovum produced by a very small insect. In this 

 case the huge excess of spermatozoa would mask the fact that 

 some of them were impotent. 



No experiments hâve been undertaken to prove or disprove 

 this, but possibly the fact that the hirtaria-pomonaria crosses, 

 in vvhich we hâve the same disparity of size, do producc females 

 may hâve some bearing on the matter. 



In the case of point 2 as a séries of elaborate investigations 

 into the cytological conditions of the ova and spermatozoa of 

 ail the species and hybrids is now being carried out, the results 

 of which will be published later, it would be unwise to give any 

 spéculations hère. 



Lastly, we come to the tempting, though defective, Mendelian 

 explanation of the facts. 



As was mentioned before, L. hirtaria, P. pomonaria and 

 P. lapponaria form one compact group, whereas /. zonaria, 

 I. grœcaria, I. italica, I. alpina form another just as natural. 



To explain our facts, let us no assume that the germ cells of 

 the maies of the first group are homozygous in respect to sex, 

 and simply bear male-ness, while the females are heterozygous 

 in the same respect, with femaleness dominant. 



On the contrary, with the second group, we must assume that 

 the reverse condition holds, i. e. that the maies are heterozygous 

 and the females homozygous in respect to male-ness, maleness 

 again being récessive. 



