THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 219 
often almost circular, anterior end only slightly attenuated, border of 
suture exhibiting folds or crimpings varying in number from 7 to 9. 
Shell: Substance dark and somewhat glittering, possessing a marked 
resistance to chemical reagents; warmed with concentrated sulphurie 
acid the valves fall apart; stronger heating effects their complete 
destruction. Valves 2, superior and inferior, with a tclerably thick 
ridge or welt along the border (line of junction), visible very plainly as 
a ridge on transverse view. 
Capsule: Wall tolerably thick, glittering, inclosing a cavity occupied 
by the coiled filament which appears paler than the wall; showing, 
with the normal extrusion of the filaments, a very noticeable diminu- 
tion of volume, whence the conclusien that (as with the thread-cells 
proper) such extrusion is the result of the pressure of the stretched 
elastic capsular walls. The capsules are destroyed by gently warming 
with concentrated sulphuric acid. Filaments extruded under the 
influence of potassium hydrate solution, glycerin, and especially con- 
centrated sulphuric acid; also by mechanical pressure. The extrusion 
produced by the last means is frequently abnormal and very irregular, 
the filament being ejected ina more or less spiral form, or only incom- 
pletely, or sometimes through arupture in the capsular wall, either into 
the shell cavity, or through the shell, or, in the last case, more probably 
between the (by the pressure) partially loosened valves. Biitschliaddsa 
few interesting remarks to the effect that the capsules, so constant in 
the Myxosporidia, doubtless have some important and yet to be discov- 
ered function. 
Sporoplasm: Mostly very delicate, cloudy, granulated, nearly filling 
the posterior portion of the shell cavity, projecting forward im the 
median line and on the outer side of the capsules; this projection could 
not be traced all the way around the capsules. Containing a variable 
number of granules. Vacuole,! frequently quite plainly visible even 
in the fresh state as a circular or oval clear spot. It becomes more 
prominent, however, after the addition of dilute acetic acid or iodine 
solution and then shows @ dark, somewhat granulated membrane and a 
number of rather pale granules strewn through the contents, resisting 
all stains,” according to Biitschli sometimes invisible, a result that he 
attributes to great condensation of the protoplasm. Some spores 
appeared to possess 2 vacuoles, but upon this point Biitschli was not 
certain. 
'This is Biitschli’s description of his ‘‘ nucleus.” 
2A circumstance explained (but erroneously) by Biitschli as being due to a failure 
of the stain to permeate the shell. He says the nonstaining can not be taken as a 
contraindication of the nuclear nature of the structure in question, as the protoplasm 
also resists the stain. From my own experience I should say that would depend on 
the kind of stain used, plasmatic stains generally being, nuclear stains generally not 
being, retained. 
