ArTHORS ABSTRACT OF THIS PAPER ISSUED 

 BY THE BIBLinaRAPHIC SERVICE, JANUARY 12 



THE OOGENESIS AND EARLY EMBRYOLOGY OF 

 ASCARIS CANIS WERNER^ 



A. C. WALTON 



NINE PLATES AND ONE TEXT FIGURE 

 (X)NTEx\TS 



I. Introduction ri27 



II. Literature . . 52S 



III. Material and methods oS') 



IV. Experimental evidence 530 



A. Oogonial development 53.5 



B. Oocytes 538 



1 . First maturation division 538 



a. Prophase 538 



b. Metaphase 549 



c. Anaphase 552 



d. Telophase 5.53 



2. Second maturation division 554 



C The fertilization j)rocess -inC) 



1. The formation of the male pronucleus 557 



2. The development of the male and female pronuclei 559 



3. Fertilization 5(J1 



4. Early cleavage 562 



V. Discussion 567 



VI. Summary 578 



VII. Bibliography 580 



I. INTRODUCTION 



The work in this paper, on the oogenesis of the common 

 nematode of the dog, Ascaris canis Werner, is a part of a broader 

 investigation on the gametogenesis of this intestinal parasite. 

 Previous articles (Walton, '16 a, '16 b, '16 c) have dealt with 

 the spermatogenesis of A. canis Werner; with the systematic 

 relationships of A. canis Werner, A. felis Goeze, and A. triquetra 

 Schrank; and w4th the mitochondria of A. canis Werner, re- 

 spectively. In the present paper the attempt is made to follow 



1 Contributions from the Zoological Laboratory of the Museum of Compara- 

 tive Zoology at Harvard College, No. 307. 



527 



