THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 97 



and Coccidia), which it is necessary, at least nntil further iufonnatioii is obtained, 

 to regard as distinct. 



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

 myxosporidian capsule and tlie falciform bodies of the gregarine spore. 



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

 the Gregarines maybe parasitic and not genetic j Litliocystis schneideri 

 is regarded as a vegetable. 



In 1879 Leuckart' recorded his opinion against the gregarine nature 

 of the Myxosporidia, remarking that: 



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

 with the Gregarines, not merely because they lack the shell-wall which surrounds 

 the gregarine spore {Pneudonavicellen-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 

 pliases falls with the psorosperm-sacs into one. 



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

 cetes. In his myxosporidian paper ^ (upon Myxidium lieberltuhnii) 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. P'urther, they possess the followiiTg nongregarine characters: (5) the 

 manifold jteculiar protoplasmic movements, (6) the "tbread-drawing" substance, 

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

 characters 1 to 4 demaiuls the separation of the Myxosporidia from tlio gregarine 

 phylum. Further, while Lieberkiihu's opinion 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 known which simultaneously lacks both 

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

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

 many exclusively myxomycetoid characters. Moreover, in Lieberkiihu's time many 

 sub.sequently discovered myxosporidioid, myxomycetous, and mycetozoan characters 

 were still unknown. 



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

 species, although it is not concealed that tlie presence of pigment (yellow, brownish 

 yellow, dark brown, blackisli brown) is highly 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 myxoraycete characters must not, 

 liowever, 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 i)y progressive 

 adaptation to restricted and new life conditions. 



' Die Par.asiten des Menschen, 2 ed., p. 245. 



-Tagt'ld. 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. Anzoiger. 1880, 

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

 pp. 358. 3.59. 



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

 F c 92 7 



