MATURATION OF OVUM OF ALCYONIOM DIGITATUM. 9501 
FERTILISATION. 
I tried to bring about artificial fertilisation in several ways, 
and without doubt a certain number of ova were impregnated, 
but only in two cases did I observe anything that one might 
reasonably suppose to be a male pronucleus. It was in both 
instances in the form of a small resting nucleus, lying in the 
centre of the egg, without centrosome or archoplasm (Fig. 5). 
ive, /7/- 
Fic, 6.—Section of a blastomere with nucleus dividing mitotically. 
(8S. J. H., del.) 
Fic. 7.—Section of an embryo showing mitotic nuclear figures. 
(S. J. H., del.) 
The spermatozoa have spherical heads with conical points. 
It was not possible with the magnification (Zeiss apochrom. 
oil immersion) to assure myself of a middle piece, or to 
differentiate the “head” into any of its component parts, 
since I did not stain these bodies. It is quite possible that 
the nuclei (Fig. 5) are really first segmentation nuclei, though 
in what way formed I am quite unable to state. From their 
