280 Genetical Studies in Moths 



than one per brood ; (3) when such are encountered they are indistin- 

 guishable from pure 0. autvmnata, are fertile, never (no matter how 

 paired up) behave otherwise than as pure autumnata ; (4) the dilutata $ 

 X autumnata ^ lot display a great lack of viability in the pupal condition. 



(22) Both sets of males are fertile but no imago has ever been 

 reared from back crosses in which they took part. 



(23) A larva endowed with wings appeared in one of the autwm- 

 nata $ x dilutata </ broods. 



(24) Certain crosses including all three forms autumnata, filigram- 

 maria and dilutata were obtained; owing to the influence of the dilutata 

 female used in their production, the same failure in viability as marked 

 the Fj lot from dilutata $ and autumnata ^ was manifested. 



(25) The crosses between 0. dilutata and 0. filigrammaria failed, 

 apparently through lack of physiological affinity. 



(2G) The haploid chromosome numbers of dilutata, autumnata and 

 filigrammaria are 30, 38, 37 respectively. 



(27) An almost perfect reduction division takes place in the gameto- 

 genesis of ^i filigrammaria ? x autumnata </ hybrids, only one or two 

 chromosomes failing to find mates. 



(28) No pairing of homologous chromosomes takes place in prepara- 

 tion for the maturation divisions of either of the ^i dilutata x autumnata 

 hybrids ; no reduction division, therefore, occurs. 



(29) Bacterial disease in which even the germ cells were affected 

 attacked the larvae in many cultures ; in such broods gametogenesis 

 was postponed, thereby necessitating delayed emergence. Though in- 

 fected, females of the cross autumnata $ x dilutata ^ appeared at their 

 accustomed time. 



(30) Fertile ova were obtained in the intergeneric cross between 

 Ghnmatobia horeata $ and 0. autumnata (^ ; all, however, failed to hatch. 



(31) No ova were obtained from the reciprocal cross to this or 

 from either of those possible between Cheimatohia brumata and 0. 

 autumnata. 



