180 EEPORT 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 ((Z), 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 (/). Meanwhile the spore has changed 

 from pyriform to ellipsoidal, and the hyaline protoplasm has become by degrees 

 granular. 



As soon as the chromosomes have reached the poles an annular constriction becomes 

 visible at the equator of the spore as well as of the nucleus (</) ; between the daughter 

 chromosomes, achromatic spindle fibers are very plainly observed. Soon at the 

 ecjuatorial 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 so sharply. The annular constriction grows 

 gradually inward aud subsequently forms the partition wall dividing the 2 spore 

 halves. Meanwhile the familiar after-formation of the chromosomes (i) 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 (?). 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 (pi. 5, fig. lla-6). 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, iu the usually homo- 

 geneous nucleus, of structures (pi. 5, fig. 11«), 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 (pi. 5, 

 tig. 6) and the spores are scattered with considerable force around the body cavity. 

 They then mostly lie (pi. 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 (pi. 5, fig. 9) with finely granu- 

 ulated protoplasm and a distinct homogeneous nucleus. Size 3 to -1 u. No movement 

 or transition into the a«iooboid stage (which transition is, however, regarded as very 

 possible) could be demonstrated. The manner of infection also remains unexplained. 



JSature. — 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 Henueguy and 

 Th^lohan in some decapods and by them ranked with the Myxospondia. 



Schewiakoff, however, doubts the myxosporidian nature of the Cijdops parasite. 

 Henneguy and Th61ohan 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 

 ThelohaniaaTj^eciea, asthe latter have no amoeboid stage, the globular cysts (sporoblaets 

 of H, «fe Th.) are of constant size (14>«), and have always 8 spores with a different 

 Btraotnre. 



