THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 209 
genic matter. The vacuolic contents further resemble the latter in 
being insoluble in alcohol. Spores kept in this liquid preserve their 
reaction towards iodine. The vacuolic matter shows a further resem- 
blance to glycogen in its solubility in alkalies. Acids modify it so that 
after their action it no longer exhibits the iodine reaction. Thélohan 
was never able to obtain the reduction of the cupro-potassium solution. 
Pfeiffer! regards it as a nucleus, as does also Weltner.? 
My own observations are in entire accord with those of M. Thélohan. 
The structure in question never colors with any staining reagents 
nuclear or plasmic. It stains (alcoholic specimens) with iodine, exactly 
as stated by Thélohan, and is, [ think, unquestionably a vacuole. 
The vacuole is single, subglobular, usually central or subcentral, 
differentiated negatively (unstained against a dark ground) by staining 
reagents, and positively (dark brown against a light ground) by iodine. 
Granules (‘ globules,” ete.)—As late as 1884, Balbiani® regarded 
these as latent capsular germs, destined to develop into accessory cap- 
sules at the period of reproduction. 
These granules appear to be of three kinds: 
1. “Globules” present in fresh material. Those situated far forward 
(usually found at the side of, and apparently connected with, the 
capsule) were first observed by biitschlit in Myxobolus miilleri, and 
subsequently by Thélohan® in J. oviformis. I have also seen them in 
M.macrurus. According to Thélohan, these are fatty, as they blacken 
strongly with osmic acid and dissolve in alcohol. 
2. “Granules ” distributed irregularly through the plasma are men- 
tioned by Biitschli (loc. cit.). 
3. The pericornual nuclei. The “ gtanules” forming this series are 2 
in number, minute, brilliant, subsymmetrically situated near both the 
lateral cornua and the posterior extremity of the capsule. These bodies 
were first noted by Miiller.© Subsequently (as above mentioned), Bal- 
biani regarded them as capsular germs. 
In 1881 Biitschli described at some length the different appearances 
presented by these bodies in Myvobolus miilleri (p. 220). 
1Die Protozoen als Krankheitserreger, 1891, 2 ed., p. 17. 
2 Sitzungs-Ber. Ges. Naturf. Freunde Berlin, 1892, p. 32. 
’Compt. Rend. Acad. Sci. Paris, 1863, Lvu1, p. 160; ine sur les Sporozoaires, 
1884, p.144. In the latter place he says: 
“One remarks in the cavity of the psorosperm other small corpuscles which appear 
as refringent globules to the number of 3 or 4, symmetrically disposed, often placed 
at the base of the twin vesicles. I have considered these small globules as vesicles 
with a filament in a rudimentary state, destined to be developed at the moment of 
reproduction, for at this moment the psorosperm contains 3 or 4 vesicles with fila- 
ments. Biitschli has attacked this manner of view, nevertheless I believe I should 
maintain it.” 
4 Ztschr. f. wiss. Zool., 1881, xxxv, p. 637, pl. 31, fig. 2, 
5 Annal. de Microgr., 1890, m1, p. 211, pl. 1, fig. 8. 
6 See p. 240, pl. 28, fig. 6g. 
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