248 REPORT OF THE CO>nriSSIONER OF FISH AND FISHERIES. 



71. Myxobolus medius Thololiau, 1892. PI. 31, figs. 2-1. 



(Cf. tiiilcd psorosperms of kiduey of Gastcrosieus acuhaiiis Lieberkiihn. 1854, 

 Miiller's Archiv., 1854, p. 357 (see p. 185) ; myxosporidian spores of G. acttle- 

 aiua and of G. pungitius, Tb^loban, 1890, Annul, de Microgr., ii, pp. 198-200, 

 209, 211, pi. 1, figs. 1, 18 (last^<7(^ Thelohan, letter); ih. Tlieloban, 1890, 

 Compt. Rend, liebdom. Soc. Biol. Paris, ii, p. 604.) 



Hevvesjujia media Th(51oban, 1892, Bull. Soc. pbiloniat. Paris, iv, p. 17*3. 



Myxobolus medius Gurley, 1893, Bull. U. S. Fisb Com. for 1891, xi, p. 416. 



Ecnneguya media Brann, 1893, Ceutralbl. f. Bakt. n. Parasitenkde, xiv, p 739. 



Myxobolus mrdius Braun, 1894, Centralbl. f. Bakt. n. Parasitenkde, xv, p. 87. 



Cyst iione; myxosporidium unknown. 



Spore formation. — Pansporoblast apparently raonosporogeuetic (see 

 pi. 31, fig. 4, reproduction of Tlielolian's fig. 18). 



Spore.— Fusiform; lengtli, 20 to 22 /i (Tliclohan, 1802); total leiigtb, 

 24 to 30 jd {ibid., 1890); shell striate; tail present, resembling especially 

 that of M. psorofspermicus, curved close against tlie body during 

 development, straightening only after rupture of the pansporoblast 

 membrane; nuclei unknown; vacuole present. 



Habitat. — Renal tnbtilcs and ovary of Gastcrosteus aciiJcatus L. 

 (stickleback); renal tubules and ovaiy of Pygoateus pungitius (O-siuned 

 stickleback). 



Effects. — The following x^robably apply to this species, to M. brevis, 

 and to Gliloromyxum elegans: 



Upon the kidney, Thelohan's observations are as follows : 



Tbe organ is often almost entirely invaded. Upon section one sees nearly all tbe 

 tubes completely obstructed by psorospermic matter. Tbe canaliculus invaded is 

 dilated and attains relatively enormous proportions, the entire kidney being conse- 

 quently enormonsly augmented in volume, and its function evidently must be almost 

 completely abolished. A remarkable fact of this invasion of the renal canaliculi by 

 the Myxosporidin is the small amount of disorder that they occasion. Beyond the 

 dilatation of tbe tubes one observes only a little augmentation of volume of the nuclei 

 of tbe epithelium. The cells are otherwise respected, and I have never seen the 

 Ijrotoplasm of the mj'xosporidium invade them or insinuate itself between them. 

 This is due without doubt to the dilatability of the renal tubules. 



The following upon the ovary jnobably applies both to M. medius 

 and to M. brevis : 



Upon sections of this organ one sees the connective tissue invaded by the plasraic 

 masses, which separate its fasciie; certain invaded ovules have completely lost their 

 normal aspect and present in their interior more or less conllueut islets of psoro- 

 spermic matter. 



72. Myxobolus creplini Gurley, 1893. PI. 32, figs. 1, 2. 



(P,soroRperms of Jcerina vuhjaris, Creplin, 1842, Wicgm. Archiv. f. Naturgesch., 



1842, I, pp. 61-3, pi. 1, figs.A-E; ib., Rayer, 1843, Ray er's Archiv. de MM. 



Comp, I, pp. 268-9; ii»., Dnjardin, 1845, Hist. Nat. d. Helminthes, p. 644; 



"tailed" psorosperm of Jcerirm Leydig, 1851, Miillci"'s Archiv., p. 222; 



psorosperm of Acerina vuhjaris Leuckart, 1852, Archiv. f. physiolog. 



Heilkde, xi, p. 436, fig. 21e; ib., Robin, 1853, Hist. Nat. de Ve'g^t. Parasites, 



pp. 312-14; spore of Acerina vulgaris, Weltner, 1892, Sitzgs-Ber. Ges. 



Naturf. Freunde, Berlin, 1892, pp. 29-31,34). 

 Myxobolus creplini, Bull. U. S. Fish. Com. for 1891, XI, p. 418; ib., Braun, 1894. 



Centralbl. f. Bakt. u. Parasitenkde, xv, p. 87. 



