2 
Transactions of the Society. 
glass and dried without heat. The material was then covered with 
a weak solution of the ordinary iodine and potassic iodide solution 
mixed with rather less than an equal part of a saturated solution of 
potassic acetate, and the cover mounted in the same, without washing. 
This gave the organisms a very delicate greenish, or bluish-green, or 
grey tint, which showed the relations of the plasm in the heads or 
ovoid bodies very clearly, without, as far as I could judge, displace- 
ment, enlargement, or shrinkage of any moment. Unfortunately, 
such mounts do not keep well. It is from such a cover preparation 
the drawings of a grey tint have been made ; while the yellow-tinted 
figures have been drawn (in each case using the Wollaston camera 
lucida) from a cover- glass preparation made in the same way, but 
substituting a weak chrysoidine solution for the iodine and potassic 
acetate, and, after five minutes, draining closely by the aid of a point 
of blotting-paper, drying without heat, and mounting dry. Various 
other plans were tried, using ammonia chromate, iodine and potassic 
iodide, logwood, different anilin dyes, zinc chloride, gold and silver 
staining, tincture of perchloride of iron, tannin, &c. Some brought 
out points less indicated by others, as seen in various mountants. 
It has been often stated, and doubted, that the spermatozoon was 
occasionally provided with two heads to one filament, or two filaments 
to one head. I shall endeavour to show that such statements are 
correct, and not due to error in observation, or optical disturbance of 
the image by such highly refracting bodies.* 
I have been able to photograph the two heads to one filament, as 
seen in fig. r; and several examples of two filaments to one head 
are seen in fig. s. 
Here, I think, there can be no question about the reality of these 
abnormal forms. As regards the variations in the shape and union of 
the heads, I have been chiefly obliged to rely on my pencil. From 
some of the figures it will be seen how the two tails may originate. 
There is in the part near to the head a considerable thickening, with 
indication of a commencing division, which if deepened would separate 
the parts, and if continued through the length of the thickened fila- 
ment the result would be two filaments to one head. In the large 
head and filament fig. p, there were strong indications that the fila- 
ment might be split even into three. After much wearying search, 
I was rewarded by finding a spermatozoon having an abnormally 
shaped head, with three distinct filaments. Whether such a division 
is perfected in the original cell or in the receptacle, the vesiculse semi- 
nales, I can offer no opinion. As regards the origin of the two heads, 
it is difficult to suggest more than the possibility that elongation may 
occur in the head and neck with a constriction, such as eventually to 
produce the two heads. Something of the kind is seen in figs. 
I and q , but I prefer to suppose them to originate by two nuclei in 
* Sec this Journal, vi. (1886) p. 581 ; ‘ Medical World,’ iv. (1886) pp. 18-20. 
