THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 97 



and Coccidia), which it is necessaiy, at least until further information is obtained,' 

 to regard as distinct. 



He further says that he fails to see any homology between the 

 myxosporidian capsule and the falciform bodies of the gregarine spore. 



Giard (see p. 170) suggests that the relation of the "psorosperms" to 

 the Gregarines maybe parasitic and not genetic; Lit/iocystis scluieideri 

 is regarded as a vegetable. 



In 1879 Leuckart' recorded his opinion against the gregarine nature 

 of the Myxosporidia, remarking tliat: 



It appears, however, scarcely permissible at present to unite these psorosperm-sacs 

 with the Gregarines, not mei-ely because they lack the shell-wall Avhich surrounds 

 the gregarine spore (rseiidonavicellen-Behalter) but still more because the formation 

 of the psorosperms begins at a time when the organism is still more or less removed 

 from its maximum size, and such formation progresses thence during the whole of 

 the subsequent existence. What is divided with the Gregarines into two successive 

 l>ha.ses falls with the psorosperm-sacs into one. 



In several papers^ Gabriel refers the "psorosperms" to the Myxomy- 

 cetes. In his myxosporidian j)aper^ (upon Myxidium lieherldllmii) he 

 says that — 



The Myxosporidia can not be Gregarines, as they lack (1) the definite typical form, 

 (2) the differentiated membrane, (3) the nucleus, and (4) the monosporogenetic 

 centers. Further, they possess the following nongregariue characters: (5) the 

 manifold peculiar protoplasmic movements, (6) the "thread-drawing" substance, 

 (7) yellow pigment, (8) vacuoles, (9) polysporogenetic centers. The importance of 

 characters 1 to 4 demands the separation of the Myxosporidia from the gregarine 

 phylum. Further, while Lieberkiihu's ojiinion that a membrane is not essential to 

 a Gregarine might be admitted, the essentiality of a nucleus is less easily waived, 

 and the fact remains that no Gregarine is knowji which simultaneously lacks both 

 of these structures. Little satisfactory when considered alone, characters 5 to 9 

 confirm the myxomycetoid affinities of the Myxosporidia, as they are analogous to 

 many exclusivelj' raj'xomycetoid characters. Moreover, in Lieberkiilin's time many 

 subsequently discovered myxosporidioid, myxomycetons, and mycetozoan chai'acters 

 were still unknown. 



Too much stress should not be laid upon the absence of pigment in gregarine 

 species, although it is not concealed that the presence of ijigment (yellow, brownish 

 yellow, dark brown, blackish brown) is highlj- characteristic of the Myxomycetes. 



The Myxosporidia are, therefore, to be annexed (not subordinated) to the Myxomy- 

 cetes. The fact that they do not display typical myxomycete characters must not, 

 however, be ignored. Though nearly allied to the same phylum, they are phyloge- 

 netically of more recent date and represent a small, sharply defined group, interme- 

 diate between the Myxomycetes and the Gregarines, originating by progix-ssive 

 adaptation to restricted and new life conditions. 



'Die Parasiten des Menschen, 2 ed., p. 245. 



•^Tagebl. d. 51 Versamml. d. deutsch. Naturf. u. Aerzte, 1878, pp. 51, .52; Tagebl. 

 d. 53 Versamml. etc., 1880, pp. 82, 83; extracts, criticism, etc., Zool. Anzeiger, 1880, 

 III, p. 572; Zoolog. Jahresber., 1880, i, p. 161 ; Journ. Roy. Micr. Soc. London, 1882, ii, 

 pp. 358, 359. 



3 Jahresber. schles. Ges. vaterl. Cultur f. d. J. 1879, lvii, pp. 188-195. 

 F c 92 7 



