CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF 

 THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD 

 COLLEGE.— No. 280. 



THE 'REFRACTIVE BODY' AND THE 'MITOCHONDRIA' 

 OF ASCARIS CANIS WERNER. 



By A. C. Walton. 



Received June 2, 1916. Presented by E. L. Mark. 



The work of Mayer ('08), Romieu ('11), Meves ('11), Faure- 

 Fremiet ('11), Wildman ('12) and Romeis ('12) on Ascaris megalo- 

 cepliala, and that of Marcus ('06) on Ascaris canis, has shown that the 

 refractive body of the sperm is formed in the vas deferens shortly 

 before the process of copulation takes place. Their work has also 

 shown that the cytoplasmic granules which surround the nuclei of 

 the nuclei of the spermatids are the so-called ' mitochondria.' Marcus, 

 working on what he supposed to be A. canis, was the first to recognize 

 the source of the refractive bodies. The present writer has elsewhere 

 shown that the form worked on by Marcus was, however, not A. canis 

 but another, as yet unplaced, nematode. It remained for Wildman to 

 follow out more completely the history of the formation of the ' refrac- 

 tive body ' and its relation to the ' mitochondria ' in A. megalocephala 

 and to show that Marcus's conjecture was an actual fact. Inasmuch 

 as the work of Marcus was not, after all, on A. canis, a description of 

 the conditions in that species may have some value. 



The writer here wishes to express his thanks to Dr. S. I. Kornhauser 

 of Northwestern University for assistance in his earlier work on A. 

 canis, and also to Dr. E. L. Mark for his helpful advice and criticism 

 in the completion of this paper. 



'The Refractive Body.' 



Marcus in A. canis, and Mayer, Romieu and Wildman in A. mega- 

 locephala, have shown that the refractive body is formed by the fusion 

 of the 'refringent vesicles' of the spermatocytic stages. Wildman 

 alone gives an account of the formation of the refringent vesicles, or 



