THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 83 
THE SPORE. 
The myxosporidian spore always consists of at least 3 structures, viz: 
a shell, one or more capsules with filament, and the single mass of 
sporoplasm. In My«obolus (p. 207) there is also sometimes present a 
fourth structure—the tail. 
Pfeiffer! regards the myxosporidian spore as the equivalent of the 
individual falciform germs (sporozoites) of the Coccidia. 
THE SHELL. 
This was noticed by even the earliest observers, who commented upon 
its most prominent features, viz: its extreme transparency and resist- 
ance to the strongest chemical reagents. Creplin? was the first to 
observe the separation of the valves after prolonged immersion in 
water. It is extremely probable that the shell substance is the same 
throughout the whole group, as we find the constant shell characters 
to be the micro-chemical ones, variation appearing to be rather struct- 
ural than chemical. This substance is thin, very transparent, insolu- 
ble in the strongest acids and alkalies in the cold, certainly in some, 
and probably in most species destroyed by (soluble in?) concentrated 
sulphuric acid at its boiling temperature;® usually with little affinity 
for staining reagents. The shell possesses a minute pore (or pores) 
for the exit of the spiral filaments. 
Two types of shell are (provisionally at least) to be distinguished. 
These are the bivalve shell, and a type in which no bivalve structure 
has been detected. 
The first type comprises 2 subtypes, viz: (a) plane of junction of 
valves coincident with the longitudinal plane; characteristic of Myxo- 
bolus; and (b) plane of junction of the valves perpendicular to the 
longitudinal plane; characteristic of the Cystodiscide and the Chloro- 
myxide. 
The second type is found in the Glugeide and in Myxidium lieber- 
kiihnii. 
Tail.—Confined within and described under the genus Myxobolus 
(p. 207). 
CAPSULES AND FILAMENTS. 
MORPHOLOGY. 
Capsule.—Always pyriform, consisting of a thick, elastic, brillianc, 
ordinarily opaque wall encompassing a central cavity; wall drawn out 
' Die Protozoen als Krankheitserreger, 1891, 2 ed., p.8. 
2 Wiegmann’s Archiv. f. Naturgesch., 1842, 1, p. 63. 
3 Balbiani asserts (Journ. de Microgr., 1883, vil, p. 202) that boiling sulphuric acid 
does not affect the shell. This Biitschli (Ztschr. f. wiss. Zool., 1881, Xxxxv, p. 634) 
denies, stating that strong heating with sulphuric acid destroys entirely the shell 
substance. My own experience with several species tallies exactly with that of 
Biitschli. 
