The Ohio ^h^aturalist, 



PUBLISHED BY 



The Biological Club of the Ohio State Uni'versity. 

 Volume VI. MAY, 1906. No. 7. 



TABLE OF CONTENTS 



Griggs— A Reducing Di\i.-ion in Ascaris 519 



DUERANT— Descriptions of New Mallophaga 52S 



Claassen— Key to the Species of Liverworts Kecognized iu the Sixth Edition of Gray's 



Manual of Botany 530 



Keli.erman and York— Additions to the Flora of Cedar Point. I 540 



A REDUCING DIVISION IN ASCARIS. 



Robert F. Griggs. 



For a long time, comparatively speaking, Ascaris has stood 

 in the way of a consistent rational interpretation of the phenom- 

 ena of reduction. It has been regarded as the one case in which 

 the divisions of oogenesis and spermatogenesis were proven to 

 be equational and not qualitative. The growing appreciation, of 

 the bearing of Mendel's Law and the course of recent work on 

 reduction have served to make it more and more of a stumbling: 

 block in the way of those who tried to understand the mechanism 

 of heredity. So great is our faith in the uniformity of nature 

 that it was impossible to believe that Ascaris was unique. Either 

 the theories of reduction built on the observed facts must be 

 insufficient or there is something yet unobserved in this form 

 which would bring it into harmony with the law. 



It was for this reason that Tretjakof (8) undertook the prob- 

 lem and published simultaneously two papers on the Oogenesis 

 and spermatogenesis of Ascaris. His- conclusions were similar 

 to those reached in the present study and apparently he saw^ 

 many of the same sorts of figures as has the present writer, but 

 his drawings are not conclusive and as Gregoire (3) says,* 

 simply open the question anew. The same may be said of the 

 work of Moszkowski (7) whose paper is unillustrated except for 

 four text figures. 



It is, then, a matter of considerable satisfaction to be able 

 to present what seems to the writer conclusive evidence that 

 the reduction division of Ascaris is a true Reducing Division in 

 Weisman's sense. 



=:- =;-- =:= " de plus il faut avouer que les figures de Tretjakof, sont fort diflficiles a eluci- 

 der et qu'il est malaise de se faire une opinion d'apres leur inspection. 



'• Les recherches de Tretjakof montrent que I'Ascaris n'etait pas encore completement 

 etudi6, mais elles ne me semblent pas elucider definitivement cet ojet difficile." 



