180 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
chromosomes which lie close to the delicate but perceptible threads of the achro- 
matic spindle. Regarding the spore from the posterior end (d), the chromosomes 
are seen to be 8, and to lie rather peripherally. After the formation of the nuclear 
plate, a halving of the chromosomes takes place in the equator (e), the halves reced- 
ing until they reach the poles of the nucleus (f). Meanwhile the spore has changed 
from pyriform to ellipsoidal, and the hyaline protoplasm has become by degrees 
granular. . 
Assoon as the chromosomes have reached the poles an annular constriction becomes 
visible at the equator of the spore as wellas of the nucleus (¢); between the daughter 
chromosomes, achromatic spindle fibers are very plainly observed. Soon at the 
equatorial constriction, an annular thickening of the spore membrane forms (h), 
running obliquely to the longitudinal axis, from above downward. In this stage the 
membrane (or external border) of the nucleus becomes indistinct and the fibers of the 
achromatic spindle also do not stand out sosharply. The annular constriction grows 
gradually inward and subsequently forms the partition wall dividing the 2 spore 
halves. Meanwhile the familiar after-formation of the chromosomes (7) takes place 
in the daughter nuclei, the nuclear membrane becomes again more distinct, and the 
achromatic fibers are scarcely visible. 
[Page 24] In the next stage (k) a distinct division wall between the 2 spore-halves 
is observed and the daughter nuclei show a finely reticular appearance, 
whence result later homogeneous nuclei (1). Division of the daughter spores soon 
takes place. 
A somewhat peculiar phenomenon was often observed. Among the many dividing 
spores some were encountered with their anterior (narrower) ends more or less inti- 
mately united (pl.5, fig. Lla-b). Schewiakoff could observe neither the union nor 
the division of the 2 spores. As, however, they differ essentially from the observed 
division stages, it may be questioned whether we have not here to do with a 
conjugation. This conjecture is strengthened by the presence, in the usually homo- 
geneous nucleus, of structures (pl. 5, fig. lla), which remind one of the nuclei of 
many conjugating Infusoria. 
The spores increase considerably in number, the spore cyst becoming ultimately 
entirely filled by them. After a couple of days the cyst bursts at one place (pl. 5, 
tig. 6) and the spores are scattered with considerable force around the body cavity. 
They then mostly lie (pl. 5, fig. 7) in great masses, or in groups of 3-5, on the muscles. 
As to the further fate of the spores nothing definite is known. After about 2 days 
they lose their homogeneous appearance and show an indication of a granular condi- 
tion. Four days later they possess an irregular form (pl. 5, fig. 9) with finely granu- 
ulated protoplasm and a distinct homogeneous nucleus. Size 3 to4u. Nomovement 
or transition into the amceboid stage (which transition is, however, regarded as very 
possible) could be demonstrated. The manner of infection also remains unexplained. 
Nature.—Without doubt Schewiakoff says, sporozoan. Schmeil, he says, considered 
it myxosporidian. (See above; the conjecture was Biitschli’s.) These parasites, 
especially the spores, have a great similarity to those found by Henneguy and 
Thélohan in some decapods and by them ranked with the Myxosporidia. 
Schewiakoff, however, doubts the myxosporidian nature of the Cyclops parasite. 
Henneguy and Thélohan gave their forms this place on account of their discovery 
of the filament. They only observed this extrusion a few times under the action of 
hydrochloric or nitric acid, and it was difficult to evoke. Since Schewiakoff could 
not discover either filament or capsule, he did not feel justified in referring the 
Cyclops parasite to the Myxosporidia. He, however, neglected to employ strong acids 
and alkalies, which is, he says, perhaps the reason of the failure. 
It appears tolerably certain that the Cyclops parasite is not identical with their 
Thelohaniaspecies, asthe latter havenoamesboid stage, the globular cysts (sporoblasts 
of H. & Th.) are of constant size (14), and have always 8 spores with a different 
structure, 
