194 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



back. The forms babitant on tliese 2 fishes are identical, difiering only 

 a little in the size of the cysts (all fide Thelohau). Subcutaneous cysts 

 of Aphya alba { = Oohius minutus and G. alhm). In the last the deform- 

 ity is even greater than in G. aculeatus. 



Kature. — For Gluge's opinion, see p. 93. 



Effects. — Even where the tumors occupy the internal surface of the 

 opercle the fish did not appear to be hampered in its functions. Those 

 which carry the tumors on the fins, nevertheless move the latter as 

 freely and actively and execute all movements with the same facility as 

 the sticklebacks not so afiected. The tumors may be carefully removed 

 without injuring the fish, which appears as well as ever after the opera- 

 tion. Upon careful dissection, Gluge was unable to find any change in 

 the intestine or in the blood. Thelohan (1890, p. 203) states that in 

 certain cases the muscles are compressed and atrophied by pressure of 

 the tumors, and the viscera are also compressed and no longer present 

 their normal i)osition or relations. 



II. PLEISTOPHORA Gurley, 1893. 



Etymology: 7r?L£iCT70f, very niauy; ^epEiv, to carry. 



Bull. U. S. Fish. Com. for 1891, xi, pp. 409, 410; ih., Brann, 1894, Ccntralbl. f. 

 Bakt. u. Parasitenkde, xv, p. 86. 

 Definition (provisional as regards negative characters).— (7%eMa? 

 destitute of a myxosporidium and in which the pansporoblast produces 

 an inconstant but large number (always more than 8) of spores ; panspo- 

 roblast membrane subpersistent as a polysporophorous vesicle j type, 

 P. typicalis. 

 29. Pleistophora typicalis Gurley, 1893. 



(Corpuscles of Cottus scorpio T\i6lohnn, 1890, Annal. do Microgr., ii, pp. 203, 212; 

 ib. TlK^lohan, 1891, Journ. de Microgr., xv, pp. 145, 146; ib. Th61olian, 1891, 

 Compt. Rend, hebdom. Soc. Biol. Paris, iii, pp. 27, 28; ib. of Collus (error) 

 Th61olian, 1891, Compt. Rend. Acad. Sci. Paris, cxii, p. 170; ib. Pfeiffer, Die 

 Protozoen als Kranlclieitserreger, 2 ed., pp. 113-115; ib. Th61olian, 1892, 

 Compt. Rend. liebdom.Soc. Biol. Paris, iv,pp. 82, 83; ib. Th61olian & Heuue- 

 guy, 1892, ibid., p. 586; ib. Tli61oliau, 1892, Bull. Soc. pliilomat. Paris, iv, 

 pp. 165, 174; ib. Henueguy & Thelohan, 1892, Annal. de Microgr., iv, pp. 

 618,619,622,631,636.) 

 Pleistophora typicalis, Bull. U. S. Fish Com. for 1891, xi, p. 410; ib. Braun, 1894, 

 Centralbl. f. Bakt. u. Parasitenkde, xv, p. 86. 



Cyst. — None. 



Spore formation. — Th61ohan observed between the fibrillse small sepa- 

 rate masses of protoplasm, each with a distinct membrane and nuclei. 

 These masses w^-e 4/^ ^ long by 2-5 to 3// broad. Thelohan believed them 

 to represent the first stages of development, but emitted this opinion 

 with reserve, not having seen a sufficient series of stages. Some pro- 

 toplasmic masses inclosing several nuclei exhibit, however, intermediate 

 stages between the masses already described and the pansporoblasts. 



» "4 Cent." in Joarn. de Microgr., xv, p. 146. 



