THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 287 
hemispheres (sporoblasts, sens. strict.) which ultimately develop into 2 
spores still contained within the pansporoblast membrane. 
Development of sporoblast to spore: The fate of the 3 nucleus-like 
bodies remains in doubt. The central one Biitschli observed to develop 
into the spore-“ nucleus.” The other two do not! (as would naturally 
be supposed) develop into the capsules; on the contrary, the 2 nuclei 
disappear, while the capsules appear in the protoplasm independently 
of them. Gabriel sometimes observed the sporoblasts (i. e., spores still 
within the pansporoblast membrane) to undergo a slow progressive con- 
traction to a globular shape, showing their membrane (presumably the 
future spore-shell) to be not yet rigid. A similar contraction was seen 
by the same observer in spores with partially disorganized shells. 
Spore.—Transversely and unequally biconvex-lenticular; length, 5 yu 
(z30/", Lieberkiihn; 4 to 6 y, Thélohan); breadth, 20 , or less (Biits- 
chli; 15 to 20 , Thélohan). Shell plainly visible, sharp contoured, 
rather thick, frequently showing a delicate antero-posterior striation; 
bivalve structure unknown, sulphuric acid producing no effect. Cap- 
sules 1 in each wing’; filaments 2 to 3 times the breadth of the spore. 
Sporoplasm almost completely filling the shell-cavity, extending even 
to the wings, there surrounding, as a thin layer, the capsules. Nuclei, 
2 (fide Thélohan, letter 1893). Concerning them and the vacuole-like 
structure shown in Biitschli’s figures, M. Thélohan writes: 
The spore of Myxidium lieberkiihnii does not contain a vacuole. This is a fact of 
which I have assured myself many times. The dark streak shown in Biitschli’s 
figures belongs, without doubt, to the 2 nuclei of the plasmic mass which are often 
approximated, and, after the action of slightly elective stains, appear blended into 
a single mass. 
Exit of sporoplasm (Pfeiffer)—Easily observable by examination of 
bladder-mucus in urine of pike at 24°C. After 4 to 12 hours a scat- 
tered mass of burst shells are seen; also many spores not yet burst, 
showing the contents much more plainly separated than in fresh speci- 
mens. In someindividuals the sporoplasm is seen to flow ameeboidly 
out ‘ between the shells” (which are peculiarly unraveled) and wander 
away. 
Gabriel states that during the whole year that he studied this species 
he never saw the shell split to give exit to the sporoplasm. On the 
contrary, he describes the process substantially as follows: 
Shell undergoing a rather easily observable fluidification or resorption, its contour 
(heretefore, though thin and delicate, plainly perceptible), after a variable period, 
entirely disappearing. Sometimes during the resorption stage, always by time of 
iQn the contrary, Pfeiffer (Die Protozoen als Krankheitserreger, 1890, 1 ed., p. 98; 
1891, 2 ed., p. 182), however, states that the capsules are formed from these 2 nuclei. 
2Sometimes only 1 capsule at 1 “end,” very rarely 2 capsules together in the 
center (Lieberkiihn). Rarely ventricose monstrosities are seen with 2 capsules 
situated together at 1 ‘‘end” (Biitschli). Balbiani figures, beside the usual forms, 
others with 2 capsules in each wing. 
