98 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
In 1881, as the result of an extended study of both Myxosporidia and 
Gregarines, Biitschli! expressed his opinion substantially as follows: 
That the relation between the Myxosporidia and the Gregarines is no very inti- 
mate one is shown both by the structure of the myxosporidium and by that of the 
spore, and also by the mode of spore formation. In the last two respects the Myxospo- 
ridia can be compared with the Gregarines only in the most general way. There are, 
indeed, some observations (e. g., the dubious one of Claparéede’s on Monocystis capitata 
Leuck., and that of Gabriel on a Gregarine of Julus, the latter, however, too incom- 
plete to serve as a basis for theoretic conclusions) which render a nonencysted 
(perhaps also an endogenous) spore formation in certain Gregarines not improbable. 
The possession in common of bivalve and tailed spore sheils is an unimportant 
similarity. Above all, we have every right to regard the capsules as a character 
especially indicative of the Myxosporidia, and of these no gregarine spore has so far 
shown a trace, the two bodies found by Schneider in the Adelea spore being scarcely 
to be paralleled with them. 
These conditions [the capsules] of the myxosporidian spore speak just as strongly 
against a clo8e connection between the Myxosporidia and the Myxomycetes, as the 
spores of the latter possess no structures comparable to the myxosporidian capsule. 
The pigment found in a few Myxosporidia (Myxidium lieberkiihnii, ete.) is not to 
be compared to that of the Myxomycetes, as it is not of myxosporidian but of 
extraneous origin. Naturally, the Myxomycetes, especially in the simplest forms, 
show in their partly peculiar endogenous spore formation a certain similarity to the 
Myxosporidia, but such a similarity also exists between the Myxomycetes and certain 
Rhizopoda, Among the latter the Myxosporidia seem to possess some special relation 
with the interesting Pelomyxa, inasmuch as the latter possesses a great number of 
small nuclei, and in addition it is probable that it produces endogenously chlamydo- 
spores, which, however, show no trace of capsules. Further, in the determination 
of the systematic position of the Myxrosporidia stress should be laid upon the cap- 
sules. From everything that we know they are comparable only to the thread cells, 
which latter are exclusively animal structures which recent investigations have 
shown to be present in the Protozoa. I do not conceal that this criterion, like the 
other barriers which have again and again been raised between the animal and 
vegetable kingdoms, may be erected only to be overturned through more penetrating 
research. 
In 1890 Pfeiffer? unites into his family “ Sporidien” the Myxosport- 
dia, Microsporidia, and Sarcosporidia. He says: 
As a transition to more dangerous parasites are next to be made known the Sarco- 
sporidia, of which Miescher’s tubes in the transversely striped muscles of the warm- 
blooded animals are already known to physicians, but which are also found exactly 
similar, only with differently shaped spores, e. g., in the flesh of the barbel. 
Spore formation has, he says, no constancy, transitions being found 
towards more highly developed forms and also toward the lower mem- 
bers of the Sporozoa. Thus in the tench fully developed forms are 
found only upon the branchise and in the air-bladder. In the gall 
bladder and the cysts on the splenic artery, spore types are found which 
form, step by step, transitions to the simple pseudonavicelle of the 
Gregarines and to the structureless ovoids of the microsporidian cysts 
of Bombyx, Daphnia, ete., and to the condition observed in coccidian 
1 Ztsehr. f. wiss. Zool., XXXv, pp. 648-650; also Bronn’s Thier-Reich, 1882, I, pp. 
601-603. 
2 Die Protozoen als Krankheitserreger, 1 ed., pp. 25-27, 42, 48, 74, 
