84 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



anteriorly into a duct wliich pierces the shell near its anterior extrem- 

 ity, affording- exit for the filament. Wall usually taking (sometimes 

 retaining, sometimes yielding up upon washing out) stains, especially 

 the nuclear. Thelohan ^ considers the substance composing the capsu- 

 lar wall identical with that forming the shell, as both stain in the same 

 way with safranin. From this view I must dissent, as in my experience 

 not only the optical character, but also all the prominent staining- re- 

 actions, differ. In particular the capsules are uniformly opaque^ the 

 filaments never being visible through them, even in glycerin, Avhile 

 the shell is transparent in the highest possible degree. Further, in 

 Myxoholus macrurus (other species were not tried) bismarck brown and 

 fuchsin each stain the capsule without even tinting the shell. 



Two reagents render the capsular wall transparent, thus permitting 

 the filament to be seen coiled i7i sitti.- The first is iodine water (solu- 

 tion with potassium iodide). This reagent also causes extrusion of the 

 filaments, sometimes even in alcoholic specimens (pp. 85, 120). The 

 second is strong ammonia water. I have never seen it produce extru- 

 sion of the filament. 



Biitschli^ and Balbiani^ have observed that when the filament 

 is extruded there is (" as in the thread cells proper", Biitschli) a very 

 marked diminution in the volume of the capsule, from which Biitschli 

 infers that such extrusion is produced by the pressure of the stretched 

 elastic capsular wall. 



This may be the cause of filament-extrusion, but might it not equally 

 well be interpreted as the result of such extrusion or, more properly, 

 as a co-result with the latter of a general increase of intrasporal pres- 

 sure? However this may be, it seems very probable that the filament- 

 extrusion which takes place under the influence of such energetic dehy- 

 drants as sulphuric acid, glycerin, etc., is merely a physical effect, 

 the result of the intense intrasporal endosmotic pressure. Thus in 

 several species (among others, Myxoholus transovalis) sulphuric acid 

 produces a pronounced swelling of the spore, extrusion (even in alco- 

 holic specimens) of the filaments, and finally the expulsion of the cap- 

 sules bodily, under an evidently great pressure. It can not, however, 

 be denied that the action of iodine water is not thus explicable. 



Filament. — Exceedingly tenuous, attached at its proximal extremity 

 to the capsular wall, free at its distal extremity; usually coiled into a 

 spiral; in this condition entirely inclosed within the capsule cavity. 

 Cai)able of uncoiling and of extrusion {via the capsular duct) as a semi- 

 uncoiled or a fully uncoiled (nearly or quite straight) thread whose 

 length may be many times that of the spore. That the semiuncoiled 

 condition is merely an intermediate stage between the fully coiled and 

 the fully uncoiled condition, and is not a specific character, is shown 



1 Annal. de Microgr,, 1890, ii, p. 207. 

 sztschr. f. wiss. Zool., 1881, XXXA^ p. 636. 

 3 Journ. de Microgr., 1883, vii, p. 204. 



