GENETIC STUDIES ON FLOUR-MOTH 425 



the appearance of cleft seems to be correlated with drying out. 

 It has also been noticed that when few cleft appeared, the tongues 

 were but slightly cleft. 



Six pairs of normal produced 307 normal and 24 cleft, a few 

 cleft appearing in each fraternity. Conditions were rather vari- 

 able as regards humidity. 



Three fraternities from normal parents were reared under dry 

 conditions. They consisted of 55 normal and 19 cleft; 27 normal 

 and 8 cleft, and 116 normal and 40 cleft, respectively. The 

 cleft showed tongues cleft practically to base. Pairings were 

 made of cleft from the last fraternity, but conditions were ex- 

 tremely dry and only one pair produced offspring, 3 moths with 

 tongue cleft to base. Results indicate that we have here a 

 recessive gene which expresses itself only under more or less 

 arid conditions. The three fraternities reared from normal 

 under dry conditions, when summarized, show 198 normal to 

 67 cleft, very close to 198.75 to 66.25, the monohybrid expectation. 



Two pairings of normal by deeply cleft produced under moder- 

 ately dry conditions 95 and 89 normal, respectively. Moths 

 from the former fraternity produced 262 normal to 51 cleft and 

 moths from the latter fraternity produced 789 normal to 114 

 cleft. Conditions were somewhat variable during the rearing 

 and eclosion of these Fo moths. When summarized there were 

 1051 normal to 165 cleft. The expectation from, a monohybrid 

 cross would be 912 to 304, which shows that cleft apparently 

 falls below expectation. 



In the later course of the work a very high humidity was 

 maintained. Under these conditions a pairing of a normal by 

 a cleft from the segregating generation summarized above pro- 

 duced 148 normal to 11 cleft. Since one of the parents was 

 cleft and cleft appeared among the progeny we would expect 

 to have a one to one ratio, the ratio from heterozygote by re- 

 cessive. The deficiency of cleft may be explained by the high 

 humidity. Under these conditions four pairs of cleft by cleft 

 produced 134 normal and only 12 cleft. 



The irregular appearance of cleft may then be explained by 

 the effect of environment. Further work is desirable to give 

 added corroboration of this theory. 



