THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 235 
resistant; contents whitish, consisting of spores, with more or less 
granular detritus. 
Spore.—Outline spatular, approaching roundish-oblong; untailed; 
length 14 to 17 yw, breadth 8°5 py, thickness 5 to 6 yu. 
Shell substance thin, almost perfectly transparent, insoluble in cold 
and moderately warm concentrated sulphuric acid, quickly destroyed 
when heated with the concentrated acid to near its boiling point; 
insoluble in concentrated solution of caustic potash, cold or hot. 
Valves separating in sulphuric acid (cold, concentrated), equally con- 
vex, the spore on transverse view appearing symmetrical ou both 
(superior and inferior) sides of the wide ridge. Greatest convexity of 
valves well forward (at about the junction of the anterior with the 
second fourth of the length;) ridge index nearly 4. 
Capsules 2, pyriform, of equal size, containing a coiled filament visi- 
ble (in iodine water) through the capsular walls; capsules drawn out 
anteriorly into the ducts, orifice visible. Methyl-green stains the 
capsular walls bright green; the filaments, sporoplasm, and shell not 
-atall. Under this treatment there are differentiated in the uniformly 
bright green capsular walls several dark green granules. Sometimes 
only 2 are seen, and these are then often situated approximately in the 
long axis of the capsules. Other specimens are seen with 4 or 5, which 
are usually arranged without marked regularity, generally, however, 
being collected near the center. Their nature is problematical. Their 
presence, position, and numerical range appear to be constant. 
Sporoplasm: The outline was not accurately traced, but the results, 
obtained by staining, suggest that upon the superior surface it may 
perhaps extend to the anterior end of the shell; upon the inferior sur- 
face if only reaches the posterior ends of the capsules. Upon this 
view of the relations, the capsules would indent the inferior surface of 
the sporoplasm. <A similar condition appears to have been observed 
in other species (pl. 34, fig. 3d). It is obvious that between the greater 
(but partial) anterior projection of the sporoplasm upon the superior 
surface in M. macrurus, and its complete anterior extension upon one 
surface in the present species, various transitions might occur, and I 
believe that this greater anterior projection affords, even in the absence 
of valvular inequality, a criterion for the discrimination of the superior 
from the inferior surface, the greater projection being always superior 
and the capsules always more or less inferior. 
Nuclei: Besides the deeply methyl green staining bodies in the 
capsular walls, 3 series of bodies, which have a constant position and 
stain with both carmine and gentian violet, occur. Those forming the 
first series have every appearance of being, and I believe are, nuclei. 
The second and third series are much more dubious, for if all the 
granule-like particles which stain with gentian violet are to be regarded 
as nuclei, the number of the latter must be reckoned as 1 or 2 score. I 
have, therefore, merely described the appearances presented by the 
