THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 199 



Tlio discoveiy of the capsule settles tlie question in favor of its myxo- 

 sporidiau nature. It is tluis neither a sarcosporidian nor a transitional 

 form (Henneguy and Thelohan, 1892). 



Microscopic technique. — Henneguy fixed by alcohol, osmic acid solution, 

 Flemming's, Perenyi's, or Kleinonberg's liquids, dehydrated, paraftined, 

 sectioned, affixed with Mayer's albumen, and stained, preferably with 

 gentian violet (Ehrlich's) and eosin. Parasites (also nuclei of muscles, 

 connective tissue, epithelia, nerves; which, however, can be washed out) 

 violet; muscles rose-red. Picro-carmine; muscles red, spore^ yellow. 

 Safranin; tissue nuclei red, spores same, but fainter. 



T, octospora dift'ers from T. giardi in the smaller size of the panspor- 

 oblast, and apparently also in the absence of thickening of its mem- 

 brane. 



Pathological anatojny. — Macroscopic :Easilyrecognizable by the chalky 

 or porcelaneous opacity^ which forms a constant and characteristic sign 

 of the presence of these Myxosporidia. Opacity limited to the muscles 

 invaded, consequently varying in extent with the degree of infection ; 

 in slight (and in the beginning of all) cases being limited to some 

 white strife in one or several abdominal segments, or only one or two 

 segments (most frequently then the first ones, the disease appearing to 

 progress from before backwards) are opaque white. Ad maximum, the 

 entire body becomes white except the region of the heart and stomach 

 which always, and some parts of the claws, antennae, beak, and abdom- 

 inal segments which usually, remain transparent. These exceptions 

 constitute the only difference between this condition and the opacity 

 produced by heat or alcohol. 



Microscopic. — Low powers: In examining a teased or slightly com- 

 pressed muscle fragment, one immediately perceives, besides the normal 

 primitive fiber bundles (easily recognizable by their transverse stria- 

 tion), elongated spaces parallel to these bundles, contrasting strongly 

 therewith, and apparently filled with a peculiar finely granular sub- 

 stance. Dimensions of spaces approximating those of the normal 

 fiber bundles; their transverse diameter, however, a little greater. 

 Number of spaces varying ^^ari^fl.sNS'i*, and the intervening sound tissue 

 varying inversely, with the intensity of the infection, the opacpie spaces 

 being in contact or more or less widely separated by sound fiber bun- 

 dles. The proportion of the fibrilhe invaded is best ai)preciated in 

 transverse sections of the muscles. In extreme cases nearly all the 

 fibers may be afiocted. Longitudinal sections show the parasite in the 

 form of violet chains between the rose-red normal fibrilljc (gentian 

 violet; safranin). 



Higher powers: At first sight one would l)elieve that each of these 

 productions is entirely composed of a i>arasitic mass interposed 

 between the jirimitive fibers, but a more thorough examination shows 



'TLo same opacity is found in tho mnsclos of Callionymuit hjra, Cottus scorpio, aud 

 BarhuH barbun, and outside the uiusclcs the parasites exhibit the same color. 



