170 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
Habitat.—Body cavity of Hehinocardium cordatum (sea-urchin), par- 
ticularly against the test between the mouth and subanal plastron, and 
especially toward the conical point which terminates the plastron 
inferiorly; also frequently on the inner side of the actinal curvature 
of the intestine. 
Nature.—Giard says: 
I have found nothing resembling the Gregarines, and the whole of the facts 
observed lead me to approximate the parasite not to the lower animals, but to the 
lower plants (Myxomycetes and Chytridinew); on the other hand, the spores being 
identical with those described as arising in the cysts of the Gregarines, one may ask 
whether the relation of the Psorospermie to the Gregarines is not a relation of para- 
sitism rather than of genetic bonds. : 
Prof. Biitschli, the only other author who has (as far as I know) 
commented upon this form, says: 
- 
It may indeed be possible that an organism as yet unfortunately only briefly de- 
scribed by Giard, his so-called Lithocystis schneideri, occupies a sort of middle ground 
between Gregarines and Myxosporidia, since it combines the plasmodioid nature with 
the production of spores similar to the Myxosporidia, together with the development 
of sickle-shaped germs in these spores. Unfortunately, however, as said, Lithocystis 
has not yet been fully described, so that the decision is at present somewhat difficult. 
Prof. Lankester? places Lithocystis among the genera of the Mywxo- 
sporidia. Pteiffer® says that this species forms ‘a transition to a still 
unknown side.” 
Remarks.—First as to Giard’s upinion, which is entitled to especial 
weight as being derived directly from a study of the form itself, while 
Biitschli’s is here to a certain extent an opinion of an opinion. In 
Giard’s article I fail to find the slightest indication of a desire to approxi- 
mate Lithocystis to the Myxosporidia. True he calls it a ‘‘psorosperm,” 
but he uses this term in a very vague sense, its scope appearing to be at 
least equivalent to that of the term Sporozoa. Further he states that: 
The whole of the facts observed lead me to approximate the parasite not to the 
lower animals but to the lower plants (Myxomycetes and Chytridinee). 
Then he argues that since the spores of Lithocystis are identical with 
the spore-like contents of the gregarine cysts, perhaps the latter 
(which he also denominates “ psorosperms”) are not gregarine spores, 
but gregarine parasites. 
Prof. Biitschli, however, says that while its spores agree with those 
of the Gregarines in containing falciform germs, Lithocystis possesses 
in common with the Myxosporidia, a plasmodioid nature and the pro- 
duction of similar spores. 
1Ks wiire sogar moglich, dass ein bis jetzt leider nur fliichtig yon Giard beschrieb- 
ner Organismus, seine sogenannte Lithocystis schneideri, eine Art Mittelstufe zwischen 
Gregariniden und Myxosporidien einnimmt, da er das plasmodienartige Wesen mit 
Erzeugung ihnlicher Sporen wie die Myxosporidien, sowie der Hervorbildung 
sichelf6rmiger Keime in diesen Sporen vereinigt. Leider ist jedoch, wie gesagt, die 
Lithocystis noch nicht eingehend beschrieben so dass ihre Beurtheilung bis jetzt 
etwas schwer fillt (Bronn’s Thier-Reich, 1882, 1, p. 602). 
2Encycl. Britan., 1885, 9 ed., x1x, p. 855. 
3Die Protozoen als Krankheitserreger, 1890, 1 ed., p. 49. 
: 
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