284 REPORT OF tHE COMMISSIONER OF FISH AND FISHERIES. 



The description is based upon the (in the main) accordant results of 

 Lieberkiihn, Balbiaui, Blitsclili, and Pfeiffer, particularly upon those 

 of the last two observers. Grabriel's accordant results have been incor- 

 porated, his divergent ones mostly footnoted. 



Life-history (Pfeiffer). — Emerging from the spore, the young myxo- 

 sporidiu-n (until now the sporoplasm) next penetrates int)the inte-ior 

 of the red bloail corpuscles or of the cells of the bladder epithelium. 

 Its intracellular existence continues until its increasing size ruptures 

 the cell wall, when it escapes, differentiates its own protective ecto- 

 plasmic layer, and resumes amoeboid movements. Finally endogenous 

 (pansporoblastic) spore formation takes jjlace, the spores altimately 

 become free, and the life-cycle is complete. 



Cyst none. 



Mi).vosporidinm} — Form varying much with age; at exit from vspore 

 globular-amoeboid: while within, and at the time of exit from the 

 epithelial and red blood cells, roundish: older forms cylindrical, ribbon 

 or club shaped, or irregularly amoeboid, presenting a very grotesque 

 appearance, with branches, forkings, and long appendages. Size vary- 

 ing with'age up to a maximum length of 300 /< (Biitschli) by a breadth 

 of 13G //. Youngest myxosporidia colorless; older ones colored yellow- 

 ish or reddish or brownish-red by inclusions of extraneous pigment in 

 the endoplasm. Myxoplasm, in all but the youngest stages, presenting 

 a clear differentiation of ectoplasm and endoplasm. 



Ectoplasm forming a rather thick, very transparent, colorless, deli- 

 cate, finely granular layer, containing none of the characteristic endo- 

 plasmic elements; end in contact with the mucous membrane, colorless, 

 destitute of granules, leafy or j)ronged for attachment. Opposite end 

 richest in granules and in pigment, free-floating, usually rounded; free- 

 floating forms partly agreeing with the above, diflering, however, in 

 being destitute of pronged processes, showing at times some peculiar 

 differentiations, particularly the appearance shown on pi. 44, fig. 3, 

 where it seems permeated by a system of canals. One end of body 

 often more or less plainly radiate-striate, the usual distinction between 

 the ectoplasm and endoplasm being here absent. This Prof. Biitschli 

 regards as the attached (pronged) end. Also not rarely are seen a series 



' Gabriel believed that the bladder does not furnish a suitable euvironmcut for 

 metasporal development, consequently the latter must, he thinks, take place in or 

 via the external world. In his opinion the myxosporidia living within the bladder 

 represents not normally developing, but progressively degenerating forms. Such 

 development as occurs within the bladder, by which apparently the way has been 

 prepared for the replacement, at least within certain limits, of the perishing mother 

 organisms, does not exclude the possibility of ripe spore-containers or free spores 

 finding their way to the outer world and there under favorable (but as yet unknown) 

 conditions developing. This supposition, a necessary postulate, becomes a certainty 

 when it is remembered that only thus [by active or passive migration] could the 

 parasite have reached the bladder. Probably repeated, though perhaps (as indicated 

 by the variations iu their occurrence) not continuous, infection-immigrations occur. 



