DEVELOPMENT OF PARACOPIDOSOMOPSIS 39 



eighteenth day. The beginning of degeneration is marked by a 

 foreshortening and twisting of the body. The larva becomes 

 immobile and soon disintegrates (figs. 87 to 90). These larvae 

 apparently perform no function, for there is no evidence that 

 they break down the tissues of the host preparatory to assimi- 

 lation by the sexual larvae. They disappear at least a week 

 before the sexual larvae are set free from their envelopes. 



As one cannot follow the course of development of a single 

 egg, but must depend upon series of sections and dissections, it 

 is impossible to determine whether every polygerm eventually 

 produces asexual larvae. It is possible that some do not. For 

 the same reason, it is difficult to determine the exact number of 

 asexual larvae produced b}^ a given egg. This in part is due to 

 the fact that these larvae are formed continuously from the 

 third to the fifteenth day, and those first developed degenerate 

 before the last ones appear. The largest number of larvae found 

 in a single case is fifteen. The data collected from dissecting 

 a large number of infected caterpillars, reared in the laboratory, 

 indicate that no more than twelve or fifteen such larvae are pro- 

 duced in a single egg. 



In conclusion, I should like to point out some of the more 

 important problems which need further study. These are: 

 1) The exact origin and the late history of the nucleolus; 2) the 

 morphology of the sexual larvae, with especial reference to the 

 origin of germ cells; 3) the morphology of the asexual larvae, 

 which should be compared with that of the sexual larvae; 4) 

 the causes underlying the origin of mixed broods and asexual 

 larvae. 



6. SUMMARY 



1. There is one generation of Paracopidosomopsis for each 

 generation of the Autographa moth, at least for the fall months. 



2. The parasite will deposit its egg in the host egg at any time, 

 but does not parasitize the young caterpillar after hatching. It 

 lays one or two eggs at each oviposition. In about two times 

 out of three two eggs are deposited. 



