CHROMOSOMES IN COREID HEMIPTERA. 8 I 



It was fun her -npposed that if an egg is fertilized by a spermato- 

 zoon bearing the idiochromosome an embryo will result whose 

 nuclei all have an even number of chromosomes, similar to the 

 oogonial group-, but if fertilized by a spermatozoon lacking that 

 chromosome, the embryonic nuclei will have an odd number of 

 chromo-ome- -imilar to the spermatogonial groups. Accordingly 

 i In- former will be- females, the latter males. It should be pos- 

 -ible. then, to distinguish the sex of an embryo by an inspection 

 of the embi \oni, -omatic) chromosome groups. 'Again, it" the 

 number of < hroni.^omes in the male and female pronuclei could 

 be accurately determined just before the first cleavage spindle 

 i- loniied. it would afford additional evidence of the dimorphi-m 

 ot the -perni.ito/oa and the relation this condition bears to sex- 

 p reduction. 



II. MAIKKIAL AND METHODS. 



The insects were brought into the laboratory or gnvnhon-e 

 and pi. u id in rages in which their food plants were growing. 

 1 1' M- the\ p. i ire. I readily and laid their eggs either on the plant- 

 or on the -ide- or bottom of the cages. The breeding period- of 

 the tcnii gener.i employed differ widely. Anasa may be found 

 pairing mi -i|ii.i-h plants in the vicinity of New York or YVood- 

 llolr i.uK in July, the eggs being laid in clusters on the under 

 -in 1 ! i lie leaves, but specimens kept in a greenhouse o\er 



t lie \\ inti-r laid early in May. Chelinidea, brought from the south 

 and kept in nhouse during the winter, began to la\ ii- 



hi-ter- ol in the latter part of March. Archimerns begin- 



la\ ing on i he ^"Idenrod in the vicinity of Ne\\ York in the latter 

 I MI! "i M.i\ or tir-t of June. The eggs are laid singly, and it 

 \\a- found impo--ible to collect sufficient numbers in the field 

 -o tli.u .ill thi'-e n-ed were taken from caged individuals. Pro- 

 tenor al-o l.i\ - ii- eggs one at a time and, in the laboratory, rarely 

 make- an\ attempt at fastening them to any object, but drops 

 them to tin 1 bottom of the cage where they were collected in small 

 i|iiantitie-. In addition to these, a number of egg;- were taken 

 from the oviduct- of Anasa and Protenor. 



The eggs "I" the lour species differ markedly in size, Archimerus 

 ha\ ing tin large-t and Protenor the smallest, those of Anasa and 



