Vol. XXXIII. August, 1917. No. 2 



BIOLOGICAL BULLETIN 



STUDIES ON THE BIOLOGY OF 

 PARACOPIDOSOMOPSIS. 



III. MATURATION AND FERTILIZATION. 1 



J. T. PATTERSON. 



INTRODUCTION. 



In the second paper in this series (Patterson and Porter, '17) 

 an account of the spermatogenesis was given. It was shown 

 that males reared from unfertilized eggs carry the haploid 

 number of chromosomes in their germ cells, and that as a conse- 

 quence the first maturation division is abortive, while the second 

 results in producing two equal spermatids, and hence two similar 

 spermatozoa. The purpose of the present paper is to give an 

 account of the maturation of the egg, and of fertilization. 



It was originally planned to report on the maturation process 

 both in fertilized and unfertilized eggs, but my series of the 

 latter has proved to be very incomplete, so that the present 

 account is based entirely on a study of inseminated eggs. How- 

 ever, it is highly probable that maturation is identical in the 

 two types of eggs of Paracopidosomopsis, as Silvestri ('06) has 

 found to be the case in Litomastix. 



It is not a difficult matter to obtain material for the study of 

 maturation. The best way is to place a few non-parasitized 

 moth eggs in a closed vessel containing a large number of female 

 parasites. In the course of an hour each host will have deposited 

 in it several eggs of the parasite sometimes as many as twenty- 

 five or thirty. The host eggs, thus serving as containers for the 

 parasite eggs, can then be fixed as desired. No difficulty has 



1 Contribution from the Zoological Laboratory of the University of Texas, 

 No. 132. 



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