Gynandr amorphous Lepidoptera. 320 



to von EngelhardfcJ who has described and figured them, 

 show a condition opposite to that met with in the Eug 

 gynandromorphs. 



Morgan's third and most important contribution to this 

 subject, "Mosaics and Gynandromorphs in Drosophila," 

 was made in L914, and gives an account of those which 

 appeared in his mutant slocks of the fruit fly. In some of 

 ilicni the male side or male portions showed maternal 



characters, in o! hers paternal ;i,nd in others both maternal 



and paternal characters. The first group would lit in with 

 Boveri's theory, the second with Morgan's, but the third 



cannot be explained by either, and must he due lo " mitotic 

 dislocation" occurring at an early cleavage stage. To 

 prove this, Morgan devised an experiment. He crossed 

 a, [c]nu\u/)ro.so/ihJI,a. homozygous for the sex linked charac 



ters of yellow body colour and while e\es with a, male with 

 normal sex-linked allelomorphs, grey body colour and red 

 eyes, but possessing in addition the recessive non-sex- 

 linked character of ebony body colour. 



One gynandromorph was found amongst many thousand 



offspring. Jt was partially male on one side, partially 

 female on the other, but, on hot h sides had a grej body and 



red eyes. This proves that the male side had received a 

 sex-chromosome from the father, the male in Drosophila 

 being heterozygous for sex, and a non-ebony chromosome 

 from the mot her. 



The female side also showed characters derived from 

 both parents. 



Morgan concludes that at some early stage of division a, 

 sex-chromosome failed to pass from one pole and became 

 lost. 



He also points out that all three groups of mosaics 

 and gynandromorphs can be explained on this hypothesis, 

 whereas neither of the other hypotheses will cover more 

 than one of the three groups. 



This was the view which I put forward independently 

 and supported by the conditions met with in ha bed 

 gynandromorph hybrids and in heterochroic gynandro 

 morphs. Several halved gynandromorph hybrids have 

 been met with, and all have shown characters derived from 

 both parents on both sides. One such is described by 

 Standfuss in a hybrid Satufnia pavonia .] 8. spvrn ,, 

 the others occurred in Amorpha hjbridus Steph. (*s r . occUntus 

 <$ x A. populi $). 



TRANS. ENT. SOC. LOND. 1916. — PARTS III, IV. (AMU I. ' I 7) Z 



