170 REPORT 0]r THE COMMISSIONER OF FIStt AND FISHERIES. 



Hahitat. — Body cavity of Uclmiocardium cordatiini (sea-iircliiu), par- 

 ticularly against the test between the mouth and subanal plastron, and 

 especially toward the conical point which terminates the plastron 

 iuferiorly; also frequently on the inner side of the actinal curvature 

 of the intestine. 



Nature. — Giard says : 



I have found uotbiug resembling tlie Gregariues, and tlie whole of the facts 

 observed lead me to approximate the parasite not to the lower animals, but to the 

 lower plants (Myxomycetes and Chytridinew); ou the other hand, the spores being 

 identical with those described as arising in the cysts of the Gregariues, one may ask 

 whether the relation of the Psorospermice 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 giound 

 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 beeii fully described, so that the decision is at present somewhat difricult. 



Prof. Lankester ^ places Lithocystis among the genera of the Myxo- 

 sporidia. Pleifier^ says that this species forms "a transition to a still 

 unknown side." 



jRemarA's.— First as to Giard's opinion, 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 Bporozoa. Further he states that: 



The whole of the facts observed lead me to approximate the parasite uot to the 

 lower animals but to the lower plants (Myxomycetes and Chyiridinem). 



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 uot 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. 



'Es ware sogar moglich, dass einbis jetzt Icider nur fliichtig von Giard bcschrieb- 

 iier Organismus, seine sogenannte Lithocystis schneideri, cine Art Mittelstufe zwischen 

 Gregariniden und Myxosporidien einnimmt, da er das plasmodienartige Wesen mit 

 Erzouguug iihnlicher Sporen wie die Myxosporidien, sowie der Hervorbildung 

 sichelformiger Keime in diesen Sporen vereinigt. Leider ist jcdoch, wie gesagt, die 

 Lithocystis noch nicht eingehend beschrieben so dass ihre Beurtbciluug bis jetzt 

 etwas schwer fallt (Bronn's Thier-Reich, 1882, i, p. 602). 



2Encycl. Britau., 1885, 9 ed., xix, p. 855. 



'Die Protozoen als Krankheitserreger, 1890, 1 ed., p. 49. 



