KARYOKINESIS AND ITS RELATION TO FERTILIZATION. 247 
at the most, say that a “ mingling ” of microsomes with one 
another occurs in such a way that it is impossible to distinguish 
the male from the female during the process. In fact, we come 
from van Beneden’s male and female loops to male and female 
microsomes, and we shall be able to answer the question 
about the more minute processes of fertilization and about 
the hermaphroditism of cells, only when we succeed in dis- 
tinguishing male from female microsomes by means of some 
reagent. 
The recent statements of Bohm (81) from Kupffer’s laboratory 
in Munich are well worthy of study in this respect. According 
to him, the male and female pronuclei which are formed after 
the entrance of the spermatozoon in the lamprey divide into 
pieces (Spermatomeriten, Karyomeriten). These pieces then 
form two separate groups, although lying close together, and 
one can distinguish for along time the two kinds of “ merites,” 
the male from the female, by microchemical tests. Each 
merite consists of an envelope with little chromatin, and a 
kernel lying within it rich in chromatin, the “ microsome.” 
The definite segmentation-nucleus—I quote textually—arises 
by the envelopes (or body) of the karyo- and spermato-merites 
fusing to form a homogeneous mass in which lie the micro- 
somes, the sex of which can no longer be distinguished. The 
chromatic portion of the karyokinetic figure is formed from the 
microsomes. We have here a clear observation of a fusion of 
the achromatic constituents, but the discrimination of the male 
from the female microsomes still baffles our microscopic 
methods. 
Quite a new point of view is opened up by a work by Weis- 
mann and Ischikawa (204a), which reached me during the 
printing of these lines. They found thatin Moina paradoxa 
the intruding spermatozoon first fuses with one of the four 
segmentation-spheres which have arisen by the second act 
of segmentation, and not with the whole of the still un- 
segmented egg-cell. In Sida copulation does not occur until 
after segmentation, but in the two-cell stage. In Daphnia 
VOL, XXX, PART 3,—NEW SER. R 
