12 Chromosomes ami Sex in Abraxas 



bilateral gynandromorph, such as is not unconimoii in Lepidoptera, 

 might be produced. Several suggestions have been made by various 

 writers as to the origin of such gynandromorphs, but a binucleate egg 

 of this kind seems as likely a cause of their production as any which 

 has been suggested. In this connexion, reference may be made to 

 the fact recorded in my previous paper on the chromosomes in Ahraxan 

 {Juuni. of Genet, ill. 1913, p. 9), that in several testes of family '12.2.5, 

 binucleate spermatocytes were not infrequent. Incidentally, Fig. 16 b 

 illustrates a point of considerable cytological interest. Around the 

 conjugating pronuclei there are conspicuous radiations in the y<)lk, 

 and it is clearly seen that these have a somewhat sinuous course in 

 the protoplasm between the alveoli which contain the yolk-granules. 

 The protoplasm near the pronuclei, and also around the polar nuclei, 

 strongly suggests that their radiations are caused by outgrowths of 

 protoplasmic alveoli, as suggested by Jenkinson'. The radiations are 

 not only sinuous, but in several cases are clearly branched. Further, 

 since the two pairs of pronuclei are near together, their radiations are 

 intermingled, and in some cases those belonging to one system quite 

 clearly cross those of the other. Such crossing can be seen in one section, 

 but I have found no case of two radiations crossing when both are 

 in focus ; since, howevoi-, the section is 10 ^ thick, and the crossing 

 radiations are well within the thickness, they cannot be much more 

 than 5 fi apart. As far as can be seen, the two sets of radiations 

 spread from centres quite independently of each other, like the roots 

 of two plants growing near together. 



I have examined eggs of only one wild female, which presumably 

 has 56 as the oogonial number, and in the fifty or more eggs which 

 were fixed, there are eight good or fair preparations showing both inner 

 and outer ecjuatorial plates. In all of these there are certainly not 

 less than 28 chromosomes in each plate (Fig. 10 a, b). In most 28 are 

 clearly shown ; in three figures, one plate might be counted as 29. 

 In the case figured, the outer plate has 27 chromosomes which are 

 clearly separate, and, in addition, a pair which might be one dividing, 

 or two at somewhat difi'erent levels. I regard 28 in both plates as 

 the most probable number, but the double chromosome may perhaps 

 correspond with the chromosome described by Seiler- which becomes 

 double in one of the second polar plates, but remains a single chromo- 

 some in the other. I find no constancy of behaviour in the eight 



' J. W. Jenkinson, Qiturt. Joiini. Micr. Science, Vol. XLViii. 1905, p. 407. 

 - J. Seiler, Zvul. Ameiger, Vol. XLi. 1913, p. 24G. 



