XII.] CONJUGATION AND SEXUAL REPRODUCTION. IJI 



of matter is proved to be impossible, it will, in my opinion, be 

 unjustifiable for science to relinquish the attempt. The con- 

 ception of vital force and the conception of fertilization as a 

 renewal of life hang more closely together than we are in the 

 habit of thinking. 



The facts of the transmission of hereditary tendencies from 

 both parents to the child, together with the facts of partheno- 

 genesis, induced me, at an early date, to look for the essence of 

 fertilization, neither in the vitalization of the ^%g^ nor in the 

 union of two opposed polar forces, but rather in the fusion of 

 two hereditary tendencies, — in the mingling of the peculiarities 

 of two individuals. The substances which come together in 

 fertilization, from the male and from the female, are not funda- 

 mentally different but essentially similar, differing only in 

 points of secondary importance. This is what I meant by the 

 statement, made shortly after the discovery of the fundamental 

 phenomena of fertilization, that the two germ-cells which unite 

 together, are in the proportion of one to one, that is that they 

 are essentially alike. 



If this conception be valid, the above-mentioned view as to 

 the extrusion of polar bodies, propounded by Minot, Balfour, 

 and E. van Beneden, must be erroneous ; for a male principle 

 such as their theory demands has no existence, and cannot 

 therefore be expelled from the ovum. There is no male or 

 female principle, but only a paternal and maternal substance. 

 If, on the other hand, Minot's Gonoblastid Theory be sound, it 

 follows that my view, which finds the essence of fertilization in 

 the union of the different hereditary tendencies of two indivi- 

 duals, must be abandoned. 



It seemed to me possible to settle the question by means of 

 parthenogenesis. If parthenogenetic eggs develope without 

 first expelling polar bodies, then Minot's theory, the ' compensa- 

 tion theory' as O. Hertwig has recently called it, receives 

 material support : if however polar bodies are formed by them, 

 it is impossible that such bodies can represent the male 

 principle of the ^g%. I succeeded in proving the existence of a 

 polar body, first in the ovum of a parthenogenetic Daphnid, 

 Polyphemus oculus, and later, in conjunction with Ischikawa, in 

 the parthenogenetic eggs of various other species of Daphnids, 

 and also in some of the Ostracoda and Rotifera. Blochmann 



