1903.] PHILLIPS—A REVIEW OF PARTHENOGENESIS. 275 
& 
A REVIEW OF PARTHENOGENESIS.' 
BY EVERETT F. PHILLIPS, 
HARRISON FELLOW IN ZOOLOGY. 
(Read October 16, 1903.) 
_ GENERAL INTRODUCTION. : 
In the great majority of cases the sex cells disintegrate unless 
they unite with the products of the opposite sex of the same 
species, but in many cases in the animal kingdom cells are given 
off from the germinal epithelium which, without fertilization, are 
able to undergo development, as is manifested by cell division. 
That these are true ova is evident from their origin, appearance, be- 
havior and fate, and the only difference between these and eggs 
requiring fertilization is that they have in them the ability to divide 
mitotically without receivirig the external stimulus given by the 
male sex cell. To this phenomenon the name Parthenogenesis is 
applied. 
The importance of facts of this kind cannot be overestimated, 
especially from the standpoint of cytological investigation. The 
various ways in which these eggs behave during maturation and the 
sex relations connected with the different kinds of Parthenogenesis 
give us most valuable guides in our study and afford invaluable 
material toward the solution of that much debated problem—the 
determination of sex. 
In view of the importance of the subject and the scattered con- 
dition of the literature, it has seemed desirable to give a brief 
summary of the most important work done, together with a litera- 
ture list of all important papers. Most attention has been given to 
the case of the Honey Bee, since it was on this form that Dzierzon 
worked and especially since the most conflicting theories have 
been advanced concerning it. A somewhat lengthy discussion of 
this one case will make clearer what follows concerning other 
species, but it is hoped that this will not make it appear that I con- 
sider this the most important case, but that it is simply used as a 
basis for the later discussion. 
The preparation of this paper was begun at the suggestion of 
Prof. E. G. Conklin to fill partially the need of some such 
review. I wish at this time to express my appreciation of the help 
1 Contribution from the Zoological Laboratory of the University of Penns) 1- 
vania. 
