286 REPORT OF TUE COMMISSIONER OF FISH AND FISHERIES. 



both varieties may be retracted and again extruded; some of these 

 processes are, bo^Yever, optical illusions, being views iu optieal section 

 of transverse ectoplasmic folds (Biitsclili; Pfeift'er). 



Ama^boid movements^: Slow, well seen when examined in the urine 

 of the fish; absent (from rapid death of myxosporidium) in water and 

 many "indifterent" fluids, e. g., egg-albumen solution. Best seen in 

 l)ike's urine at 21° C; the ectoi)lasm executes very extensive ama-boid 

 movements, wrinklings, and ibldings (Pleiller). 



Spore formation} — Not confined to adult forms, but found in rayxo- 

 sporidia of all sizes. Thus few-si)ored large, and many-spored small 

 myxosporidia are often seen (Gabriel). This occurrence at ditferent 

 times is explained by successive ripenings of the different individual 

 myxosporidia composing the plasmode. Small round myxosporidia not 

 yet entirely freed from the epithelial cell-remnants often contain 2 or 

 more spores (Pfeiffer). 



Pansporoblast formation: This, the first step toward spore for- 

 mation, takes place by the differentiation within the myxoplasm of a 

 number of small, clear, transparent plasma-spheres ( pa)is2)orobIasts), each 

 consisting of one of the many nuclei of the myxosporidium, together 

 with a portion of the surrounding myxoplasm which it has attracted 

 to it. Sometimes early, and in all cases later, each pansporoblast is 

 surrounded by a thin darlc membrane,^ and is found to contain a 

 number of nuclei, usually 6. 



Pansporoblast-segmentation : Subsequently, instead of the pansporo- 

 blast consisting, as originally, of the pansporoblast membrane contain- 

 ing a single (usually sexanucleate) plasma-sphere, it comes to consist 

 of the same membrane containing two * (usually trinucleate) plasma- 



' Gabriel (loc. cit.) gives a very detailed description of these movemeuts, concluding 

 that they are so complex and peculiar as to find no parallel with the Gregarines, and 

 none appears admissible ■with the ]iseudopodial movements of the Protozoa. Special 

 emphasis is placed on the presence iu the myxoplasm of a "thread-drawing" (Faden- 

 ziehenden) substance, ca])able of emitting psciidopodioid processes, lut incapable of 

 retractinfj them. This, Gabriel asserts, finds a parallel only iu myxomycete plasmodea, 

 of -which it is an exclusive feature, Biitsclili (1881, p. GIO) has, however, observed 

 the retraction of these processes. 



- Description Biitschli's, unless otherwise stated. 



'Pfeifter couiirms. Upon examining a myxosporidium in a dilute solution of 

 eosin, or other stain, the spores stain only after rupture (by pressure on cover-glass) 

 of this membrane. Gal)riel dissents, regarding the pansporoblast as a " wall-less 

 vacuole, which first takes on the vesicular appearance described by Leydig at a 

 later stage." According to Gabriel the pansporoblast does not always persist to 

 maturity, so that in the later stages it may bo vainly sought. Gabriel was unable 

 to trace a genetic relation between the ''granules" (? nuclei) of the myxosporidium 

 and the spores, whence he concluded that the latter originate by a process, not of 

 niyxoplasmic integration but by one of secretion, the uujrphologic substratum of the 

 sporigeuous vacuoles being regarded as polysporotjcnetic centers strongly contrasted 

 with the monosporogeneiic centers of the Gregarines. 



■• Spores in this species always developed in ])air8 (Biitschli). Spores not always, 

 though usually, developed in pairs; such paired development may be absent among 

 both developing and free spores (Gabriel). 



