THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 227 
Myxosporidium.i—P feiffer has seen the exit of the sporoplasm. He 
did not have the opportunity to cultivate the spores via the over- 
hanging drop, but says such cultivation would be easy and would show 
the stage at which infection occurs. He did not actually see the 
myxosporidium penetrate the muscle cell, but he has found within that 
cell all growth-stages of the myxosporidium. The elongate myxo- 
sporidia often show, in their center, pansporoblasts containing well- 
developed spores, while at the ends these structures are smaller and 
contain only 1, 2, 4, or more nuclei. This proves that, as in the Sarco- 
sporidia (also with the tubes of Sygnathus and, fide Thélohan, with those 
of Cottus scorpio), growth takes place at the ends of the tubes. Have 
these younger developmental stages originated from germs from the 
interior of the large tube, do they proceed from residual germs of the 
first multiple infection, or do they develop from newly immigrated 
germs? A positive answer can not yet be given, but inthe barbel Pfeiffer 
regards the second mode (viz, a supplementary outgrowth from the 
germs which penetrated en masse in the first infection) as the more 
probable. In the myxosporidium tubes germs migrate from the center 
to the circumference, where they find better food conditions and through 
progressive division become new pansporoblasts (Sporenkugeln). The 
center of the cyst is also empty in the cysts of the sheep, those of 
the tench’s air bladder, and that of the kangaroo’s intestine. When 
the myxosporidia have attained a certain size, they are found free in 
the interstices of the muscular fiber. When crowded, they fuse to an 
irregular mass; only at the edges are some unfused myxosporidia to be 
seen. Hzematoidin crystals are found in the myxosporidium. 
Spore formation.—This appears in the smallest cireular cysts with 16 
to 20 germs; also in uniloculate elongate cysts thickly filled with 100 
to 200 germs. In places large granule cells are imbedded in the musecu- 
lar fiber. At another (?later) stage the dancing granules have vanished 
and the contents of the cells have separated with 10 to 20 or more pale 
globules one-third the size of the ripe germs. Also some fibrilla show 
in their interior well-developed spores, with capsules and nuclei, single 
or in rank and file (? accident; ? pressure on cover-glass). The possi- 
bility of these must be admitted, yet the contents of the capsules 
appeared to have been voided. 
Spore.—Lenticular or oval; length 12 yz, breadth 10 , thickness 6 su 
(Ludwig); bivalve, shell cavity containing sporoplasm and 2 capsules, 
the latter extruding filaments under the influence of potassium hydrate 
(Mégnin); by glycerin (Pfeiffer). 
Have the Myxosporidia resting spores?) Mega-, and micro-spores 
(differing only in size) occur; also defective spores with 1 capsule, 
with caudiform appendages, or with a subrotund form (Pfeiffer). 
Habitat.—Eneysted and free in muscles, mostly of belly and sides of 
body (never elsewhere, the liver, spleen, ovary, eggs, and gills being 
' Description, Pfeiffer’s (loc. cit., 2 ed., 1891, p. 106). 
