170 ROSCOE R. HYDE 



laid eggs which did not develop the male was found to be at fault. 

 Some of the eggs of such a female always hatched on placing her 

 with fertile males. It may or may not be that Castle's case 

 and mine are similar since they behave somewhat differently in 

 heredity. Since Castle's paper deals primarily with another 

 problem, the data upon which the above conclusions in regard to 

 the method of transmission are based are too small to base any 

 definite conclusions upon, since the influence that may have 

 entered into the experiment from the other sex is not with cer- 

 tainty under control. A glance at Mast's last conclusion will 

 show that the male also may have been at fault. 



CONCLUSIONS 



1. One kind of sterility in Drosophila ampelophila is due to 

 some defect, probably in the oviduct of the female, so that she is 

 unable to deposit her eggs. 



2. The defect is transmissible through inheritance by at least 

 some of the brothers and sisters of the affected females when 

 mated to a fertile race, to the granddaughters, but apparently 

 not to the sons or daughters or grandsons. It is therefore reces- 

 sive and affects females only. 



3. The process of inbreeding brothers and sisters cannot be 

 held to be responsible for this condition, but probably serves to 

 bring it out when latent in a strain by making the necessary 

 combinations. 



4. The character seems amenable to selection and can be made 

 to affect fully 50 per cent of the females or can be practically 

 eliminated by making the proper selections. 



5. It seems very probable that sterility as it affects the male 

 bears no causal relation with sterility as it appears in the female. 



6. The defect in the female behaves after the manner of a 

 Mendelian character in that it reappears after skipping a genera- 



