^Jomiai;M7yJ^^^^^^ PROGHESS OF MICROSCOPICAL SCIENCE. 313 
These are the spermatozoa in the young state; the nucleus becomes 
the head, and the protoplasm which surrounds it becomes the tail. In 
the salmon the adult spermatozoa have an elongated head, pointed in 
front and wide behind, like a fish's head, or like an ace of hearts on 
cards. This head is composed of two parts, which are separated one 
from the other by a superficial groove. Each half is rounded behind 
in the form of a club. There is behind the head an enlargement 
which seems to correspond to the body of certain other zoosperms, but 
which really has no distinctive character. The tail is very long, and its 
movements are not of a " bounding " character, but an undulatory vibra- 
tion. The seminal fluid of fishes is at first fluid, but it soon coagulates 
and becomes gelatinous ; but if this mass is broken up it becomes fluid 
anew. The author has even artificially fertilized the eggs taken 
from dead fishes, and in most cases with successful results. If water 
is added to the seminal mass the spermatozoal movements become very 
rapid, but if too much be added they cease quickly in most instances. 
Then the tail becomes invisible, even under the highest power. This 
disappearance he believes to be due to the sudden retraction of the 
tail, which becomes applied to the head ; and he states that if it be 
carefully watched under high powers it will be seen that the tail is 
drawn up suddenly, and that the protoplasmic mass of the head becomes 
simultaneously enlarged. The employment of reagents, like* indigo, 
carmine, &c., shows that the tail is composed of protoplasm, and that the 
disappearance of the tail is due to its being applied against and partly 
coiled around the head. 
TJie Structure and Belations of the Ovum. — The Belgian Academy's 
prize for the best essay on the ovum in the different classes of the 
animal kingdom was recently awarded to M. Edonard Van Beneden. 
MM. Gluge, Schwann, and Poelman, who made the award, have 
reported at length on M. Van Beneden's essay, which, by the way, 
extended over 442 pp. 4to. The development of the ovum has been 
described in the ' Trematodes, Cestoids, Turbellaria, Nematoids, Crus- 
tacea, Birds, and Mammals.' The reporters, while admitting the 
merits of the essay, have not hesitated to express their disapproval of 
certain parts. Indeed M. Gluge goes so far as to say that the part 
devoted to egg of the bird does not deserve any mention. The 
author's view as to the constitution of the ovum is that which he has 
already in part laid down in the communication published by him and 
M. Bessels in these pages, and it is thus expressed by M. Schwann : — 
" The general result at which the author has arrived is that the egg is 
in its origin a simple cell, whose nucleus is the vesicle of Purkinje, 
and whose nucleolus is the germinal dot of Wagner. The protoplasm 
which surrounds the nucleus completes the cell. But the primi- 
tive cell combines later with a deposit of nutritious matter, under the 
form of highly refractive globules, which he terms plasma. This 
plasma, which is variable and may be absent (as in CucuUanus), 
combines with the cell-egg in a different manner in the different 
classes of the animal kingdom. The mode of development of the 
cell-egg is the same in all animals : in those which are germigenous 
and viteUigenous — that is to say, in which the work is divided between 
