286 Prof. J. E. Salvin Moore and Miss F. Tozer. [Jan. 14, 
normally occur in half the number of the somatic chromosomes. When the 
eggs have reached the above condition, the first polar body spindle is formed 
in the manner represented in fig. 2. There are no centrosomes, and several of 
the characteristic forms of the gemini correspond to the forms seen in the 
similar stages of spermatogenesis. The division of the gemini takes place 
in the same manner as that occurring during spermatogenesis and the diaster 
of such a division is represented in fig. 3. When the first polar body has 
been definitely extruded, as in fig. 4, the nucleus which remains in the egg 
immediately proceeds towards another division; the chromosomes appearing 
on this spindle (the second maturation spindle) being in the form of rods or 
diads, such as those represented in fig. 6. Here, again, as in the case of the 
first polar body spindle, we have found in some cases that the number of 
chromosomes appearing is greater than half the somatic number. In the 
second polar body spindle, as in the first, there are no centrosomes. At the 
time the second polar body is being produced, it is often possible to observe 
a division of the nucleus of the first polar body also taking place, and the 
final result is the production of four nuclei, one remaining in the egg, two 
derived from the first polar body, and one belonging to the second polar 
body. We are at present inclined to interpret the high number of gemini and 
chromosomes appearing during the first and second polar body divisions as 
possibly due to the fact that in the first polar body division the synaptic 
chromosomes have not all united in pairs to form gemini before the division 
ensues; whilst during the second polar body division the number perhaps 
appears to be high, owing to the fact that when the rods dnd diads are 
produced they often become prematurely divided, so that, in the act of 
counting, halves may be reckoned as whole individual chromosomes. 
In a certain number of eggs a very interesting process can be observed 
resulting in the parthenogenetic segmentation of the eggs, and the process 
may extend to the production of 12 or 15 irregular blastomeres; it then 
comes to an end, the eggs apparently degenerating. The spindles found in 
these dividing eggs are typically somatic in appearance. 
This process is probably the same as that described and figured by 
J. Janosik in his account of the “ Atrophy of the Follicles of the Guinea- 
pig,’* but it is necessary to draw attention to the fact that Janosik may 
possibly have missed the point upon which we lay stress. He has failed to 
separate the process resulting in the production of polar bodies from that 
ending in irregular segmentation and degeneration of the egg cell, and he 
apparently considers the stage showing a polar body and the spindle, for the 
* “Die Atrophie der Follikel und ein seltsames Verhalten der Hizelle,” ‘Arch. f. 
Mikr. Anat.’ vol. 48, 1897. 
