NEW YORK ACADEMY OF SCIENCES 6oi 



One half the spermatozoa, therefore, receive the large idio- 

 chromosome and one half the small, the other chromosomes 

 being exactly duplicated in both. 



Correlated with this asymmetry of distribution is the fact 

 that the spermatogonial chromosome-groups do not show two 

 equal microchromosomes (as is the case in such forms as Anasa, 

 Alydus or Protenor, where an accessory chromosome is present) ; 

 but only one, which is obviously the small idiochromosome, 

 the large one not being certainly distinguishable at this period 

 from the other spermatagonial chromosomes. The final synap- 

 sis of the idiochromosomes is deferred to the prophases of the 

 second division, somewhat as that of the two equal micro- 

 chromosomes is deferred until the prophase of the first divi- 

 sion in Anasa, Alydus and some other forms. A remarkable 

 result of the difference in this regard between the forms that 

 possess and those that lack a true accessory chromosome is that 

 in the former case (Anasa, Alydus, etc.) the first division of 

 the small central chromosome is a reduction- division and the 

 second an equation-division; while in the latter case (Lygceus, 

 Ccenus, etc.) the reverse order manifestly occurs. The relation 

 of these observations to earlier ones by Paulmier, Montgomery, 

 and others was pointed out, with a discussion of their bearing 

 on the Mendelian phenomena of heredity and the problem of 

 sex- determination . 



Professor Crampton presented briefly some of the conclusions 

 drawn from the results of his work upon variation, correlation, 

 and selection among saturnid lepidoptera. The earliest studies 

 showed that eliminated individuals, when compared with 

 similar members of the same group that survive, prove to be 

 more variable and of somewhat different types ; although this 

 relation between variability and selection is not a constant 

 one. The characters utilized for these preliminary studies, 

 namely, certain pupal dimensions and proportions, were of such 

 a nature that they could not serve the pupa directly in any 

 functional manner; wherefore it was concluded that their con- 

 dition of correlation formed the actual basis for the selective 

 process, formative correlation being also distinguished from 

 functional correlation. That the general condition of corre- 



