248 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



71. Myxobolus medius TlK^lohan, 18!)2. PI. 31, ligs. 2-S. 



(01'. tailed jtsorosixa'ins of kiduoy of (iastevusicuH acuUaiuH Lieberkiihu. 1854, 

 Miillcr's Archiv., 1854, p. 357 (see p. '['><'>) ; luyxosporidian spores of G. acule- 

 aius and of G. pmif/itius, Tln'^lobau, 1890, Aimal. deMicrogr., ii, pp. 198-200, 

 209, 211, pi. 1, figs. 1, 18 {hxst fide Tliolohaii, letter); ib. Tlidlohan, 1890, 

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



Jlcniirniiya media Theloban, 1892, ]5iil]. Soc. plulonint. Paris, iv, p. 17n. 



Myxobolus mediittt (iurley, 1893, Bull. U. S. Fish Com. for 1891, xi, p. 416. 



Hcnneguya media Braiui, 1893, Ceutvalbl. f. Bakt. ii. Parasiteiikde, xiv, p. 739. 



Myxobolus mrdius Braun, 1894, Centralbl. f. Bakt. u. Parasitenkdo, xv, p. 87. 



Cyst none; myxos])oridiuui iinkiiowD. 



Spore formation. — Pansporoblast apparently raonosporogenetic (see 

 pi. 31, fi^. 4, reproduction of Thelolian's ii^. 18). 



AS>re.— Fusiform ; lengtli, 20 to 22 y< (Theloban, 1802); total length, 

 24 to 30 ju {ibid.y lSi)0) ; shell striate; tail present, resembling especially 

 that of ]\r. psorospcrmicns, curved close against the body during 

 development, straightening only after rupture of the pansporoblast 

 membrane; nuclei unknown; vacuole i^resent. 



Habitat. — Renal tubules and ovary of Gastcrosteus acuJeatus L. 

 (stickleback); renal tubules and ovary of Pyyosteus iJiUKjitius (O-spiued 

 stickleback). 



Ejfects. — The following probably apply to this species, to M. brevis, 

 and to Chloromyxum elegana: 



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



The organ is ofteu almost entirely invaded. Upon section one sees nearly all the 

 tubes completely obstructed by psorospermic matter. The canaliculus invaded is 

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

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

 completely a])olished. A remai'kable fact of this invasion of the renal caualiculi by 

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

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

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

 protoplasm of the myxosporidium invade them or insinuate itself between them. 

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



The following upon the ovary x>robably applies both to M. medius 

 aud to 3£. brevis : 



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

 masses, which separate its fasciae; 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 crepliiii Gurley, 1893. PI. 32, figs. 1, 2. 



(Psorosperms of Accrina vulgaris, CrepHu, 1842, Wiegm. Ar(diiv. f. Natnrgesch., 



1842, I, pp. 61-3, pl. 1, tigs.A-E; ib., Rayer, 1843, Ray er's Archiv. de M<«d. 



Comp, I, pp. 268-9; i&., Dujardiu, 1845, Hist. Nat. d. Helmiuthes, p. 644; 



"tailed" psorosperm of ,4 ceriwa Leydig, 1851, Miiller's Archiv., p. 222; 



psoros])erm of Acerina vulgaris Louckart, 1852, Archiv. f. physiolog. 



Heilkde, xi, p. 436, fig.21e; ib., Robin, 1853, Hist. Nat. de V<?gdt. Parasites, 



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



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

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



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



