94 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



Creplin says : 



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

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

 examined for Helminths. Since, liowever, I have seen v. Siebold's line Contribu- 

 tions to the Natural History of the Invertebrate Animals (Danzig, 1839) I believe I 

 have found somethinj:: iinalogous to them in Ihe organisms discovered by v. Siebold 

 in cysts in the small intestine of Sciara nUidicoUis, Avhich lie terms Navicella;. See 

 flf, 63 and the accompanying figures on Tab. iii. * * * Altliough some features 

 may api>ear 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 Avithin 

 that fluid, or by production from the cyst-wall. 



Dujardin^ also sujigestod the correlatiou 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 Lumhrici. 



In 1851 Leydig^ developed the gregarine theory at some length. 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 gregariuoid bodies have in contour somewhat the ap- 

 pearance of segmentation spheres. The fact that they only sliow granules does not 

 coniraindicate their gregarine nature, nor does the absence of motion, as slight 

 moiions 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 s^ovas {Navicdlenhehalier) iiH proceeding from the Gregarine, But anyone 

 who has compared the psendonavicella? and the psorosperms will certainly admit 

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

 by him in the diseased air Ijladder of Gadus callarias form one series, the dift'erent 

 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 FilariaY\\.Q, nematodes,^ says (pp. 232-233) that the 

 Myxosporidia of the i)lagiostomes 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 hcvis. 



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 



' Hist. Nat. des Helminthes, 1845, p. 645. 

 « MuUer's Archiv., pp. 226-228. 



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

 filarioid forms are referable to Trijpniwsoma. 

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



