24 1906 
The Ohio T^aturalist, 
PUBLISHED BY 
The Biological Club of the Ohio State University. 
Volume VI. MAY, 1906. No. 7. 
TABLE OF CONTENTS 
GKlG(iS— A Reducing Division in Ascaris 519 
Durrant— Descriiitions of New Mallophaga 52S 
Claa.ssen— Key to the Species of Liverworts Recognized in the .<ixth Edition of Gray's 
Manual of Botany 530 
Keli.erman .AND York — .X^dditions to the Flora of Cedar Point. I . . 540 
A REDUCING DIVISION IN ASCARIS. 
L»B«ARY 
NEW YORK 
botanical 
OARDSN. 
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 it faut avouer que les figures de Tretjakof, sont fort difficiles eluci- 
der et qu’tl est malaise de se faire une opinion d’apres leur in.spection 
Les recherches de Tretjakof montrent que I’Ascaris n'etait pas encore completement 
etudie. mats elles ne me semblent pas elucider definitivement cet ojet difficile " 
