94 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
Creplin says: 
Nothing even remotely similar has ever been seen by me in the many kinds 01 
small cysts which I have frequently found in the invertebrate animals and have 
examined for Helminths. Since, however, I have seen y. Siebold’s fine Contribu- 
tions to the Natural History of the Invertebrate Animals (Danzig, 1839) I believe I 
have found something analogous to them in the organisms discovered by v. Siebold 
in cysts in the small intestine of Sciara nitidicollis, which he terms Navicelle. See 
ff. 63 and the accompanying figures on Tab. ui. * * * Although some features 
may appear to indicate a vegetable nature, the cyst bears distinctive marks of its 
animal nature. Cyst formation precedes spore formation, the spores perhaps origi- 
nating from the granules seen in the cyst fluid, or perhaps by free formation within 
that fluid, or by production from the cyst-wall. 
Dujardin! also suggested the correlation of the ‘ psorosperms” with 
the Gregarines in the following: 
‘Perhaps it is necessary to range with these productions those that one frequently 
observes in the testicles of Lumbrici. 
In 1851 Leydig? developed the gregarine theory at somelength. In 
brief, his reasons were as follows: 
On him they made the impression of gregarine-like bodies and he knew no weighty 
reason against this view. They consist of roundish vesicles or vermiform tubes 
with a delicate membrane, and semi-fluid contents with granule masses. Fre- 
quently they appear as if a special membrane had not yet been separated from the 
contents, in which case the gregarinoid bodies have in contour somewhat the ap- 
pearance of segmentation spheres. The fact that they only show granules does not 
contraindicate their gregarine nature, nor does the absence of motion, as slight 
movions might have been present, and further in some Gregarines motion cannot 
always be detected. Further, all who have studied the Gregarines unite in regard- 
ing the spores (Navicellenbehdlter) as proceeding from the Gregarine. But any one 
who has compared the pseudonavicelle and the psorosperms will certainly admit 
the conclusion that the navicellie, Miiller’s psorosperms, and the forms discovered 
by him in the diseased air bladder of Gadus callarias form one series, the different 
members of which are related as the genera of a family. 
Further Leydig, having, as he believed, demonstrated the Gregarines 
to be life-stages of Filaria-like nematodes,® says (pp. 232-233) that the 
Myzxosporidia of the plagiostomes can perhaps also be brought into 
unison with these views, by similar connection with the round Filaria- 
like nematode which he found in the blood of several plagiostomes 
and in the parenchyma of various abdominal viscera (especially in the 
spleen-pulp) and rarely in the blood of the umbilical cord of embryos 
of Mustelus levis. 
Leuckart,* in 1852, accepting Leydig’s view that the Gregarines 
were developmental stages of nematodes, regarded the “psorosperms” 
as forming similar developmental stages, this view being based upon 
1 Hist. Nat. des Helminthes, 1845, p. 645. 
2 Miiller’s Archiy., pp. 226-228. 
3 According to Mingazzini (Boll. Soc. Nat. Napoli, 1890, 1v, p. 162, footnote 2) these 
filarioid forms are referable to Trypanosoma. 
* Arch. f. physiol, Heilkde, x1, pp. 434-6, 
