THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 181 



The presence of a contractile vacuole in tbe adult, the iieculiarities 

 in the process of spore formation, the falling to pieces of the nucleus, 

 the apparent absence of pansporoblasts, the occurrence of reproduction 

 only at and as the end of the life cycle, and the fnrther multiplication 

 by the division of fnlly formed spores, all absolutely contraindicate any 

 niyxosporidian affinities. Further, the constant presence of pigment^ 

 corroborates this conclusion, which is still further enforced by negative 

 evidence from the structure of the spore, the most prominent feature ot 

 which is, of course, the absence of the capsule. Indeed it seems safe to 

 go further and say that no organism with a contractile vacuole can, in 

 the present state of our knowledge, be regarded as sporozoan (cf. Lan- 

 kester, Encycl. Britan., 1885, 9 ed., xix, p. 854). 



PROBABLY MYXOSPORIDIA. (Imperfectly described.) 



7. Genus et sp. incert. 



Amcebiform corpuscles of gills of Cyprinus irama, Lieberkiihri, 1854, Miiller's 

 Archiv., pp.6, 7; I ib. of heart-blood of same fish," p. 14; cf. also Miiller, 

 Miiller's Archiv., 1841, pp. 491-2. 



Cyst. — Membrane so transparent that all details could be as well seen 

 before as after expression of its contents. Contents "psorosperms" 

 and amcebiform corpuscles, or amcebiform corpuscles only. 



Myxosporidium. — Numerous, partly granular, partly granule-free, 

 the latter usually smaller than the former, alterations of appearance 

 very manifold, processes rather sharp than blunt, size not equal to that 

 of a blood corpuscle of the fish ; granules extremely small, held together 

 by a mucoid substance. 



Spore. — Unknown. 



Habitat. — Encysted in the gills of Ahramis hrama L. (bream) in 

 November. 



Remarks. — Its habitat suggests that this species is probably a Myxo- 

 holus. 



8. Genus et sp. incert. 



Sarcode masses of Perca flnviatilis, Lieberkiihn, 1854, Miiller's Archiv., p. 353. 



Cyst. — Apparently no true cyst (see mention below of membrane). 



Myxosporidium. — Consisting of granular i)rotoplasm presenting a 

 great similarity to that of Chloromyxum mucronatum, very variable in 

 appearance, oval, lenticular or dendroidly branched. Size 27 to 440 fx 

 (sV to \"') ; some specimens surronnded by a structureless membrane, 

 others not; sometimes the whole substance is seen to have fallen apart 



• While it is, of course, not contended that this alone would suffice to prove a species 

 noumyxosporidian, pigmentation, such as exists in the Cijclops cyst, would raise a 

 strong presumption against its myxospoiidian nature. 



"Those [amcebiform corpuscles] of the heart blood of Cyprinus hrama completely 

 parallel in their form the above-described amcebiform masses found on the gills of 

 the fish, and are differentiated among themselves in the same way as the gill forms 

 [i. e., they are either granular or granule-free]. Their movements are, on account 

 of their small size, difficult to observe. 



