DEVELOPMENT OF COPIDOSOMA GELECHI^. 



357 



X chromosome. If such nuclei later divided in the typical 

 manner and gave rise to embryos, such embryos would be males. 

 One is encouraged to make this suggested explanation in the light 

 of Bridges' ('13) discovery of the non-disjunction of the sex 

 chromosomes in Drosophila. In Copidosoma the separation of the 

 sex chromosomes during cleavage would be a case of "somatic" or 

 "cleavage disjunction," while in Drosophila these chromosomes 

 fail to separate or "disjoin" in the reduction division of the egg. 

 In conclusion attention should be directed to the frequency of 

 Copidosoma in nature. At Woods Hole about twenty per cent. 

 of all Gnorimoschema larvae are infected with this parasite 



TABLE VI. 



TABLE SHOWING PERCENTAGE OF PARASITIZED CATERPILLARS IN THE GALLS OF 



SOLIDAGO SEMPERVIRENS. 



* Record incomplete. 

 Copidosoma. 



About 20 per cent, of the caterpillars are parasitized by 



(Table VI.). As may be seen from the table, the extent of 

 infection varies greatly in the lots of galls taken from different 

 regions (those collected on a given date are all from a single 

 locality). Plants which grow in exposed places, as along the 



