MATURATION AND FECUNDATION OF THE OVUM. 107 
E. Van Beneden’s Researches on the Maturation 
and Fecundation of the Ovum . 1 
By 
J. T. Cunningham. 
Fellow of University College, Oxford ; Superintendent of the Scottish Marine 
Station. 
With Plate X. 
A great many elaborate researches have been made in 
recent years into the series of phenomena in ova and sperma- 
tozoa which precede and accompany fecundation. By the 
synthesis of these it has been found that the series of phenomena 
is in almost all cases essentially the same ; the more accurate 
the research, the more similar have the phenomena appeared in 
different animals. With regard to the ovum, the formation of 
polar globules is the most constant and most conspicuous 
event of its history previous to fecundation. Some years ago 
it was firmly established that there is a very great similarity 
between the changes which the germinal vesicle undergoes in 
the formation of polar globules, and the process of karyokinesis 
in cell-division. 
At an earlier period it had been held that the germinal vesicle 
disappeared, and no connection had been surmised between that 
structure and the polar globules. These globules were regarded 
as unimportant drops of viscid substance expressed from the 
vitellus. In 1875 Biitschli' 3 first described a spindle in an 
unfertilized ovum. It was observed in the egg of Cucullanus 
1 ‘Arch, de Biologic,’ 1883. 
5 ‘ Z. f. w. Z.,’ vol. xxv. 
