Habits and structure of Cotylaspis insignis Leıpy. 997 
0.004 mm. The granular chromatine is very scanty in amount. The 
cytoplasmic portion of the cell, unlike the preceding stage, is greatly 
vacuolated. This condition does not appear to be artificial, since it 
is found in specimens hardened in a great variety of reagents, 
corrosive, picro-nitric and chrom-osmium-acetic. Cells of this sort 
are seen in some of the sections in the act of descending into the 
“fallopian tube” as VoELTZkow called the following upper part of 
the oviduct in Aspidogaster. As it is probably in the “tuba” that 
fertilization takes place (vid. STAFFoRD, 1896, p. 49) one would 
expect that the maturation of the egg would occur in this part of 
the ovary itself or in the tube leading to the upper part of the 
“tuba”. I did not, however, observe any ova here or any where 
with indications of nuclear activity. 
The position of the ovary in Cotylaspis is just the reserve of 
that in Aspidogaster, where the deeper portion is anterior and the 
part next the “tuba” is posterior. This difference involves only the 
ovary and the upper part of the tuba, which in Aspidogaster is 
suddenly bent on itself in the middle, while in Cotylaspis it is straight. 
The portion of the oviduct immediately adjoining the ovary has 
a very peculiar structure, unlike that found in any other trematodes 
as far as I am aware, with the sole exception of Aspidogaster and 
Cotylogaster. VOELTZKOW noticed it in Aspidogaster and applied the 
name “tuba fallopii” to it, his fig. 17 shows its position and appearance 
in Aspidogaster. It is much the same in C. insignis (Fig. 48, 49), 
the wall of the oviduct is composed of a dense layer, covered with 
flattened epithelium cells, it is pushed in at intervals, so as 
nearly to sub-divide the cavity of the oviduct into a series of 
chambers, communicating by means of a hole in the centre of the 
cross-wall. This part of the oviduct is not ciliated, the cilia beginning 
just below it. It would seen likely that these chambers serve to 
receive and retain the ova as they descend from the ovary and that 
it is here that they undergo maturation and fertilization, but I have 
never seen either ova or spermatozoa in this organ, though I have 
found the fully formed eggs, enclosed in their shell in the uterus 
only a very short distance away, so that fertilization must have 
taken place in this neighborhood. I have not succeeded in recognizing 
any muscular tissue in the walls of the tuba even in sections in 
which the muscular fibers were particularly distinct elsewhere. 
The oviduct (Fig. 5) beyond the “tuba” runs first posteriorly, 
Where it receives the duct from the yolk receptacle, then trans- 
15* 
