BIOLOGY OF PARACOPIDOSOMOPSIS. 371 



larvee degenerate. The beginning of degeneration is marked by 

 a foreshortening and twisting of the body (Figs. 23-25). The 

 larva then becomes immobile and soon disintegrates (Fig. 26). 

 So far as I can observe, the larvae perform no function. There is 

 no evidence that they break down the tissues of the host in 

 preparation for assimilation by the sexual larvae. They dis- 

 appear at least a week before the sexual larvae become free agents. 

 Whatever may be the underlying cause of the development of 

 these non-viable larvae, there is certainly no doubt as to the fact 

 that they are formed from the egg of Paracopidosomopsis. This 

 fact is established by the results obtained from controlled experi- 

 ments in which all other parasitic species have been excluded, 

 and by tracing their origin back to the beginning of their develop- 

 ment in the young polygerms. 



AUSTIN, TEXAS, 

 June 20, 1918. 



