THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 189 
first their existence is appreciable by the microscope, soon (July) they 
are visible to the naked eye, the lower end of the zooid tube losing 
its transparency and becoming milk white. In August the alteration 
becomes very marked, the cavity of the zooid being distended and 
completely opaque. 
Spore formation.—How and whence do the spores originate? In any 
case their origin is endogenous (in the endoplasm) and probably occurs 
in the manner observed by Prof. Biitschli in Myaxidium lieberkiihnii, 
where a spore membrane is formed around a trinucleate globule. In 
our case are often found, in the plasmodium, nuclei in state of division. 
Around such nuclei, which are still united by the threads of the spindle, 
a resistant shell appears often to be present. Could this be a spore? 
Korotneff is able to confirm Biitschli’s observation that spore formation 
does not mark the end of the life cycle. In M. bryozoides, however, 
the spores always appear at a definite period of that cycle, viz, after 
the complete disappearance of the nuclei of the host-cell. 
Spore.—Elongate-oval, resembling a melon seed, sharp anteriorly, 
rounded off posteriorly. Shell extremely hard, very resistant, lustrous, 
apparently with an opening at the sharp (anterior) end; no bivalve 
structure demonstrable, though empty spores are not rare. Often, but 
not always, two vacuoles are visible. In the spring he was able to 
distinguish at the anterior end of the spore a glittering point whose 
signification was unknown. It might possibly be a capsule (nemato- 
cyst; Nesselkapsel). 
Habitat.—In very considerable numbers in the body cavity of Alcy- 
onella fungosa (a fresh-water polyzoan) in the neighborhood of Moscow, 
in the beginning of summer. The infection appears to be endemic, as 
Korotneff has never observed it in southern Russia and as it appears 
to be absent from western Europe. 
Seat and pathological anatomy.—Principally grouped around the 
funicle upon which the spermatoblasts (which serve as food for the 
young myxosporidia) are produced. No tissue except the spermato- 
blastsis attacked. Repeated careful investigations showed the absence 
of myxosporidia from the polyp and from the walls of the zocecium. 
Effects —The extensive infection exerts a direct (but only a mechan- 
ical) influence on the polyp, producing, as a result of its continued 
growth, a progressive atrophy, which, by the end of August, results in 
the complete disappearance of the polyp. The infection extends itself 
through the colonies, scarcely a single zooid escaping. The death of 
the colonies occurs much earlier than it would naturally under the 
influence of cold. 
_ RKemarks.—Henneguy and Thélohan believe the reference of this 
form to the Myxosporidia absolutely justified, although the capsule has 
not been demonstrated, 
