94 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



Crepliii says: 



Nothing even remotely similar has ever been seen by me in the many kinds oi 

 small cysts which I have frequently found in the invertebrate animals and have 

 examined for Helminths. Since, however, I have seen v. Siebold's line 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 NavAceUoe. See 

 ft". 63 and the accompanying figures on Tab. iii. * * * Altliough some features 

 may appear to indicate a vegetable nature, the cyst bears distinctive marks of its 

 animal nature. Cyst formation j)recedes 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. 



DLiJardin^ also suggested the correlation of tlie "psorosperms" with 

 the Gregarines in the following: 



Perhaps it is necessary to range with these productions those that one frequently 

 in the testicles of Lumirici. 



In 1851 Leydig* developed the gregarine theory at some length. In 

 brief, his reasons were as follows: 



On him they made the impression of gregai'ine-like bodies and he knew no weighty 

 reason against this view. They consist of roundish vesicles or vermiform tubes 

 Avith 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 

 motions might have l)een present, and fui'ther in some Gregarines motion cannot 

 always be detected. Further, all who have studied the Gregarines unite in regard- 

 ing the s.-^oxCiS {NaviceUeuMUlUer) SLS proceeding from the Gregarine. But anyone 

 who has compared the pseudonavicellis and the psorosperms will certainly admit 

 the conclusion that the navicelhe, Miiller's psorosperms, and the forms discovered 

 by him in the diseased air bladder of Gadus callarias form one series, the diflcrent 

 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 

 Myxosporidia 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) aUd rarely in the blood of the umbilical cord of embryos 

 of Mustelus Uvvu. 



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 Archiv., pp. 226-228. 



3 According to Mingazzini (Boll. Soc. Nat. Napoli, 1890, iv, p. 162, footnote 2) these 

 filarioid forms are referable to Trypanosoma, 



♦ Arch, f.physiol. Heilkdo, xi, pp. 434-6. 



