448 ANNA R. WHITING. 



served in Habrobracon. The biparental males 'have all been com- 

 pletely male in external and internal morphology and in reactions. 

 The high mortality suggested above may be due to intergrades 

 that cannot survive in this species. In Lymantria the intergrades 

 occur as a result of wide crosses while in Habrobracon these males 

 come from crosses of related stocks only. 



Non-disjunction may also be considered a possibility. Bi- 

 parental males may be diploid for all chromosomes save one, the 

 sex chromosome, and thus be males although resembling their 

 sisters in appearance. 



Unfortunately Habrobracon, like the Hymenoptera in general, 

 is not ideal for cytological study. Haploid number of chromo- 

 somes seems to be eleven and they are extremely minute. Nachts- 

 heim has demonstrated (Nachtsheim, H., 1913) that in the honey 

 bee chromosomes frequently fractionate so that somatic counts 

 vary considerably being various multiples of the haploid number. 

 The author finds indications of this in another form now under 

 observation so that a very careful study and numerous counts are 

 necessary before conclusions can be drawn. 



In spermatogenesis of biparental males the first maturation 

 division is abortive, the second apparently equational as in normal 

 haploid males. This process may result in diploid spermatozoa 

 which when united to recessive eggs would give only dominant 

 triploid offspring. The high percentage of physical abnormalities 

 in daughters of biparental males and their sterility may be due to 

 their triploidy. They possess ovaries and ova normal in general 

 appearance. 



LITERATURE CITED. 



Goldschmidt, Richard. 



'27 Physiologische Theorie der Vererbung. Berlin. 

 Nachtsheim, H. 

 '13 Cytologische Studien ueber den Geschlectsbestimmung bei der 



Honigbiene. Arch. f. Zellf., XI. 

 Whiting, Anna R. 



'25 The Inheritance of Sterility and of other Defects induced by 

 Abnormal Fertilization in the Parasitic Wasp, Habrobracon 

 juglandis (Ashmead). Genetics, X., 33-58. 

 Whiting, Anna R., and Burton, Raymond H. 



'26 Quadruple Allelomorphs affecting Eye Color in Habrobracon. 

 Am. Nat., LX., 285-290. 



