138 



MISS MAUDE L. CLEGH0RN ON THE INHERITANCE OF 



the eggs were multivoltine. As this female of F x had hatched 

 from a completely multivoltine laying, it might naturally be 

 expected that, when the paternal parent was pure multivoltine all 

 the eggs laid would be multivoltine, but as only a few eggs 

 hatched it showed that the maternal parent was dominant in the 

 uuivoltine character, and that the dominance of the univoltine 

 character was inherited by the $ from the paternal parent in 

 which it ivas not a dominant character. 



It is clear that the female influences the reappearance of the 

 character in a dominant form, and shows that the descent is of a 

 sex-limited inheritance. 



In my experiments I found that the univoltine or multivoltine 

 character of the maternal parent showed itself in the layings and 

 not that of the paternal, for the character of the paternal parent 

 always appeared to be masked or suppressed. 



Besides the difficulties a sex-limited inheritance presents the 

 univoltine and multivoltine characters are not visible in the moths 

 but only in their layings, for moths which outwardly resemble the 

 univoltine parent may have a multivoltine laying and vice versa. 



When all the moths of a generation are bred inter se the 

 character of only the maternal parents can be determined by the 

 eggs laid ; but to prove that the males and females of each 

 generation are either homozygous or heterozygous, dominant or 

 recessive, they have each to be bred with pure univoltines and 

 multivoltines. So to find out the exact composition of all the 

 moths in each generation would require a multitude of experiments, 

 and I could not spare many moths from "F , for I knew that in 

 F only a very small percentage of eggs would hatch. 



The layings in F., which were laid by the F moths give a clue 

 to the character of some of the parent moths in F 2 . For the 

 maternal parents of the six univoltine layings (Table 2) must 

 have been dominant in the univoltine character, and those of the 

 two multivoltine layings, in the multivoltine character, but the 

 sixteen 50 per cent, univoltine layings point to the maternal 

 parents being heterozygous. 



Experiment B. 



From the results obtained in the Ital.-Jap. $ ana * Nistori S 

 cross (Table 3) it will be seen that although all the layings in F 1 

 were univoltine, yet there were some multivoltine, and partly 

 multivoltine layings in F„, F 3 and F 4 ; and, again, though the 

 moths of F 3 were reared from one of the multivoltine layings 

 of F.,, yet 37 layings of the F 3 moths were univoltine. 



Forty-seven moths from an F„ family of the Ital.-Jap. 2 an( ^ 

 Nistri <5 cross were tested with pure multivoltine Nistri moths 

 and the results obtained were as follows:— 



(1) Out of 21 layings of the F 2 $ s and pure multivoltine 

 Nistri d s 19 layings were entirely univoltine and 2 entirely 

 multivoltine. 



