THE MYXOSrORIDIA, OR PSOROSPERMS OF FISHES. 173 



3 or 4 together into irregular eluinps. Many such clumps had no sur- 

 rounding membrane, but some showed such a membrane containing 

 several corpuscles. The features of the latter bodies were plainly dis- 

 cernible through the enveloping membrane. The corpuscles at this 

 stage are unsplit, the valves being united for their whole length, form- 

 ing a lenticular corpuscle. Further, similar cysts were seen which 

 showed no developed corpuscles, but only large granules. Finally, a 

 number of separated valves may be seen. From these facts IMiiller 

 concludes tliat the corpuscles in question develop several in a cyst, are 

 set free unsplit, subsequently the valves separate, at first partially, at 

 last probably entirely, and then perhaps the cycle is repeated. 



Habitat. — Air bladder of Gadus morrhua (= callaHas), cod. 



Nature. — Eobin includes it among the " i)sorosperms." 



Dr. L. Wittmack ' refers to this as a " psorosperm." 



Concerning this form Prof. Biitschli^ says: 



It appears to mo quite questionable whether these psorospermiform corpiisclea 

 of tlie air bladder of Gadus callarias are to be referred to the Myxosporidia proper or 

 to the Coccidia. Their structure appears to approximate itself rather to the latter; 

 especially in the absence of the polar capsules so characteristic of the Myxosporidia. 



1 can see no myxosporidian structure in it, and have, therefore, 

 omitted it from the subclass. 



Effects. — Mucous membrane of the air bladder red and swollen, infil- 

 trated by the parasitic mass. Tail unusually thin and shrunken, the 

 soft i)arts being markedly atrophied, the muscular tissue having dis- 

 appeared. Further observation must detei-mine the constancy and 

 causality of relation between the two conditions. Such atrophy is 

 apparently not rare in Gadus, as the fishermen at Bohusliin knew the 

 disease and informed IMiiller that it rendered the fish unfit for food. 



IMiiller says that the difference between this form and the psoro- 

 sperms of fresh-water fishes is as great as that between different 

 genera of animals. 



AtrojjJiy of tail of Merlangus merlangus.^ 



The following observation pro])ably can not be better placed than as 

 an appendix to the similar disease of G. morrhua jnst described. Among 

 the Mediterranean fishes collected by Mr. Peters, Midler and Ketzius 

 noted a Gadus merlangus aft'ected with complete atrophy of the tail 

 muscles, the tail being composed of nothing but skin and bone — not the 

 slightest trace of muscular tissue renniining. Tiie junctitm of the nor- 

 mal and atrophied tissue was abrupt and was situated at the root of 

 the tail. Unfortunately, the air bladder had not been preserved. 



' Beitriige zur Fipcherei-Statistik d. doutsch. Reiflis, 1875, p. liU, footuote. 



«Bronn's Thier-Reich, 1882, r, p. rm, footnote. 



'Mullcr and Retzius, 1812, Miiller's Arrhiv., p. l'J8j soc iilso p. 172. 



