218 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
Myxosporidium.—Myxosporidium usually showing no clear difieren- 
tiation of ectoplasm and endoplasm except in thin sections, where certain 
portions exhibit very plainly a tolerably thick, granule-free exterior 
zone, possessing a great interest on account of its very distinct fine 
radiate striation. Endoplasm thickly studded with very small but 
distinct nuclei which in thin sections are, even in the fresh state, rather 
plainly visible as faint roundish corpuscles, in which dilute acetic acid 
differentiates a dark somewhat granulated membrane, a small dark 
nucleolus, and, sometimes quite clearly, fine nuclear threads radiating 
from the nucleolus to the membrane. This structure, together with 
their intense affinity for stains, permits no doubt as to their nuclear 
nature. 
Spore formation.i—This species never shows a paired spore-develop- 
ment, or a development within a pansporoblast (?; see below), the 
spores being directly imbedded in the endoplasm. ‘These spores, how- 
ever, Show indications of a similarity in their development to the other 
My«xosporidia in their origin from a trisegmented (‘ trinucleate”) plasma- 
globule, 2 of whose segments develop the capsules and the third the 
sporoplasm. 
Development of spore.2—In the myxosporidium, inclosed in a delicate 
membrane, a number of mature spores are seen, many things pointing 
to their origin from the protoplasm. They always contain 3 pale, 
almost spherical, but somewhat angular bodies. The membrane fre- 
quently shows an excavation and an opening at one end. At this end 
the 2 protocysts are situated, the protosporoplasm being remote there- 
from. Further observation shows the protosporoplasm to develop into 
the sporoplasm of the mature spore and the two protocysts to give 
origin to the capsules. The latter structures develop within the proto- 
cysts, the filament appearing first in the extruded condition, apparently 
forming a prolongation of the capsular wall. 
Subsequently, in the light of his observations on the development of 
Myxidium lieberkiihnii, Biitschli inclined to interpret thus: That the 3 
spheres (viz, the 2 protocysts and the protosporoplasm) represent 
not plasma-spheres but nuclei, the latter being, on this supposition, 
imbedded in a plasma mass which he had failed to see, probably on 
account of strong swelling and great transparency. 
The observations of Balbiani and of Thélohan, however, render it 
almost certain that Biitschli’s observations were accurate and that his 
subsequent interpretation was erroneous (see also pp. 82, 223). Upon 
this view the present species would seem to develop pansporoblasts, 
each with a single spore. 
Spore.—Lenticular-oval, anterior end sharpened, showing quite plainly 
a shallow funnel-shaped depression; posterior end rounded off; dimen- 
sions 10 to12 u by 9 to il uw. On vertical view, contour rather variable, 
1 Biitschli, 1882, Bronn’s Thier-Reich, 1, p. 597. 
8The description is Biitschli’s (Ztschr. f. wiss. Zool., 1881, xxxv, pp. 646-8). 
ee 
