GERM CELLS IN THE ARTHROPODA 157 
added in the figure from a part of the odcyte three 
sections away. AQ still further stage of fusion is 
indicated in Fig. 47, D. 
In all these cases and in fully developed eggs 
there is a distinct ‘waist line’ which can be ac- 
counted for upon the view that two odcytes fuse end 
to end as above described, the narrow part corre- 
sponding to the region of union. The conclusion 
seems warranted, therefore, that every egg when laid 
consists of two odcytes which have united end to end, 
the posterior or older odcyte being provided with 
keimbahn-chromatin derived from the chromatin of 
its nucleus, and the anterior supplied with a nucleus 
which has arisen from the disintegration of a spindle 
similar to that from which the keimbahn-chromatin 
originated. 
A number of references are present in literature to 
what have been termed “uterine,” “‘ disappearing,” 
or “aborting” spindles. Such a spindle was first 
noted by Selenka (1881) in the turbellarian, Thysano- 
zo6n diesingti. Here apparently a completely de- 
veloped maturation spindle was observed in the 
fully grown eggs after they had entered the uterus; 
then, just before the metaphase of mitosis, the spindle 
broke down and the nucleus returned to a resting 
condition. This same nucleus later gave rise to 
polar bodies as in the eggs of other animals. Similar 
aborting spindles have been described by Lang (1884) 
in several species of polyclads, by Wheeler (1894) in 
Planocera inquilina, by Gardiner (1895, 1898) in 
Polycherus caudatus, by Surface (1907) in Planocera, 
