THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 223 
Spore formation.—With the growth the number of nuclei increases by successive 
divisions! (many of which were seen to occur). Subsequently each nucleus con- 
denses around it some of the myxoplasm, thus forming the pansporoblasts. These 
grow, become elliptic, and the rudiments of the capsules appear in them, at first as 
very pale, then as brilliant bodies. The mode of their development was not entirely 
satisfactorily ascertained. They usually develop 2 in each pansporoblast, some of 
these sporoblasts containing 3 granular globules, 2 small and 1 large, which prob- 
ably develop respectively into the capsulesand the sporoplasm. Also incompletely 
developed spores were seen inclosing elements believed to be capsules in process of 
development. These were: (1) Two spherical vesicles containing each a small cen- 
tral globule placed in the substance of the spore remote from the poles. (2) Two 
small similar vesicles placed one beside the other at one pole. (3) Two pyriform 
vesicles with a small central globule, sometimes remote from each other, sometimes 
approximated to each other and situated at one extremity of the spore. These vesi- 
cles were ne doubt the small organs with spiral filaments. Their origin could 
not be clearly determined. 
Spore.—F lattened-ellipsoid, rather elongate, the two ends similar; 
length 12 to 15 41; breadth 9 to 11 «3 length of capsules 4 4“; nuclei of 
capsulogenous membrane persisting to maturity of spore; vacuole 
present; nuclei originating by continued division from a primitive one, 
not more than 4; when of this number, 2 are situated before and 2 
behind the vacuole (Thélohan, pp. 209-210). 
Degenerate forms [of this species ?] from the gall bladder may have 
3 capsules or none, and the bivalve character of the shell may be absent 
(Pfeiffer). 
Ribbons: Balbiani” has made some curious but dubious observations, 
arriving at conclusions which by no means accord with the general 
consensus of opinion. He describes an elastic, ribbon-like process 
(the ribbon) as existing along the border of each valve of the shell, 
stating that at the time of maturity of the spore (the only period at 
which such ribbons are visible, as at other periods they are closely 
appressed to the valves) they become unrolled and recurved, such action 
resulting in the splitting apart of the valves and the consequent release 
of the amceboid sporoplasm. The ribbons divide at their distal 
extremity into 2 or 3 ribbonettes. These elastic structures he regards 
as comparable to the cruciform elastic filaments (elaters) of the Equise- 
tum spore, remarking that in the Myxosporidia they serve a different 
function, their action here being valve-separation and not spore-disper- 
sal. He further says that these elastic ribbons have another function, 
viz, to maintain contact of 2 spores during what he regards as astate of 
From -Balbiani’s language it is plain that he did not recognize the vacuolic 
nature of Biitschli’s ‘‘nucleus.” Still he must have seen nuclei (and not vacuoles) 
in the later myxosporidium stages, as he states that he repeatedly observed them to 
divide. Probably Thélohan’s observation of karyokinetic division (Compt. Rend. 
’ Acad. Sci. Paris, 1890, cx1, p. 693) was upon WM. ellipsoides, though it isnot distinctly 
so stated. Among other figures he saw a spindle with an absolutely typical equa- 
torial plate. 
2Journ.de Microgr., 1883, vu, pp. 276-7: Légons sur les Sporozoaires, 1884, pp: 
1424, 
