ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 537 



with a chromatic plexus ; this nucleus divides by karyokincsis ; each of 

 the daughter-nuclei passes to one of the ends of the spore, where it 

 undergoes two successive divisions, in such a way that the spore contains 

 two groups of four small nuclei. These pass to the middle of the spore, 

 the protoplasm of which becomes divided into eight falciform nucleated 

 bodies, surrounding the "noyau de reliquat " of Schneider. This 

 nucleus does not take up staining reagents, and the term applied to it 

 is inexact, for it does not exhibit any of the characteristic reactions of a 

 nucleus ; it is formed of a mass which is more finely granular and more 

 refractive than the rest of the protoplasm of the spore. It is placed at 

 the centre, and round it the falciform bodies are organized ; it seems to 

 diminish in size during the development of the spore and to serve for 

 the nutrition of the falciform bodies. The author proposes to speak of 

 it as the central globule. 



Cystodiscus immersus — a Myxosporidium found in the gall- 

 bladder of Brazilian Batrachia.* — Dr. A. Lutz has found in the gall- 

 bladder of certain frogs and toads a parasite which would seem to have 

 no pathological significance. Macroscopically it appears as a thin round 

 transparent disc, sometimes surrounded by a whitish periphery. 



Thirty to fifty individuals may be found in one gall-bladder, and in 

 size they sometimes attain to a diameter of 1^2 mm., with a thickness 

 equal to 1/20-1/10 of their diameter. Under the Microscope these discs 

 are seen to be incased in a transparent structureless membrane, which is 

 very resistant to reagents. The organism has no power of spontaneous 

 movement. The contents of the discs are numerous vesicles, which by 

 close apposition become polygonal. They are not nucleated, and if they 

 are set free they speedily vanish, as does their delicate investing sheath. 

 The most prominent characteristic of the parasites is the spores, which 

 lie outside the vesicles, and usually in pairs. These spores are of various 

 sizes, and when ripe attain a length of 12-14 yu,, and width of 9-10 /x, 

 being oval in shape, with blunt ends. They are made up of two flaps or 

 valves and two almost spherical polar corpuscles. They contain an ex- 

 tensile filament, which exceeds the whole length of the spore four or five 

 times. "When indrawn it is spirally rolled up and scarcely visible. By 

 means of caustic potash it can be extruded. The rest of the spore is 

 occupied by a transparent plasma-mass, coagulable by reagents. 



With regard to the development of the spores, the author first 

 observed them as oval bodies containing two pale small polar corpuscles, 

 the rest of the body being dark. The latter decreases in size and clears 

 up, the investing membrane pari passu appearing, and the polar bodies 

 becoming larger. No nucleus was observed. 



» Centralbl. f. Bakteriol. u. Parasitenk., v. (1889) pp. 84-8. 



* I -^ I » 



