210 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES, 
Thélohan! was the first to recognize their nuclear nature. He first 
believed them to belong to the sporoplasm, supposing them to be situ- 
ated at its 2 antero-external angles (lateral cornua). Subsequently, 
from a study of capsule development, he’ regarded the bodies in ques- 
tion as persistent embryonal nuclei, the remnants of such development. 
He further expressed the belief that these nuclei could in some cases 
become detached from the capsules and engulfed in the sporoplasm. 
Pfeiffer? termsthem “safranophile corpuscles,” but does not comment 
upon their nature. In Myxobolus macrurus I have studied these bodies 
(which, from their position, may be termed pericornual nuclei) with 
great care, and with the following results, which apply especially to 
M. macrurus, but equally well to M. lintoni: 
1. There can be no question whatever that they are nuclei, as they 
take nuclear stains and show nuclear structure. 
2. Their presence or absence and their position (at least in the fully 
developed spore) appears constant for the same species. As regards 
constancy of position they contrast strongly with the third and fourth 
nuclei. 
3. The only question is as to their seat. It will be seen above that 
they have been regarded as belonging to the capsule and also as 
belonging to the sporoplasm. Asis implied by this difference of opinion, 
their seat is by no means easy of determination, and, after much study, 
J am as yet uncertain whether they are capsular or sporoplasmie. 
Three appearances may sometimes be seen on the same specimen: 
(a) They appear in one focus-plane almost certainly connected with the 
infero-lateral cornu; or, (b) they appear almost as certainly attached 
tothe drawn-out posterior end of the capsule; or, (c) they appear discon- 
nected from both and appear to be borne on a broad triangular spur 
projecting inwards from the shell. 
An interpretation which seems possible is that each nucleus is 
imbedded in the sporoplasm near the tip of the supero-lateral cornu, 
whence it happens that optically its position almost exactly coincides 
with that of the posterior end of the capsule. 
In some species (Myxobolus cf. linearis, M. transovalis) I failed to 
find any bodies which on account of the constancy of their position, 
etc., I could regard as the pericornual nuclei, and this absence appears 
to be here as definite a specific character as does their presence in M, 
macrurus and M. lintont. 
34. Myxobolus unicapsulatus Gurley, 1893. Pl. 13, fig. 1. 
(Psorosperm of Labeo niloticus Miiller, 1841, Miiller’s Archiv., p. 487, pl. 16, fig. 
5 a-d; ib. Robin, 1853, Hist. Nat. d. Végét. Parasites, p. 299, pl. 14, fig’7.) 
Myxobolus unicapsulatus, Bull, U.S. Fish Com. for 1891, x1, p.414; ib. of Labro 
[error] niloticus Braun, 1894, Centralbl. f. Bakt. u. Parasitenkde, xv, p. 86. 
Cyst and myxosporidium unknown. 
1 Compt. Rend. Acad. Sci. Paris, 1889, crx, pp. 920-1; ibid., 1892, cxv, p. 1097. 
2 Die Protozoen als Krankheitserreger, 1891, 2 ed., p. 7. 
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