ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 319 



mechanism is actuated by the foot, both hands are available to give to 

 the cutting knife those exact movements so essentially necessary to the 

 successful production of extremely fine, thin, delicate films ; therefore 

 the brittle substances having been treated in any of the usual ways to 

 impart tenacity and partial elasticity thereto, the knife is made to ap- 

 proach and cut into the substance of the object, either direct, diagonally, 

 or in any other desired manner, without fear of one part of the film or 

 slice being of greater thickness than another, a most important con- 

 sideration with respect to opaque or semi-opaque substances. Another 

 important feature in the device arranged as above described, is the 

 rigidity with which the object to be operated upon is maintained in 

 position during the process of cutting or slicing the same, as the means 

 for imparting motion being situated at a distance from the mechanism, 

 and the latter inclosed if desired in a protective case or box, the risk of 

 movement, or shifting of the substance from which a film is to be cut, is 

 rendered impossible." 



(4) Staining and Injecting. 



Staining Cultivation Media and its results on micro-organisms.*— 

 Dr. G. D'Abundo's object in staining cultivation media with various 

 dyes was to attempt to ascertain if any new biological characteristics 

 could be imparted to the micro-organisms cultivated thereon, and, if 

 possible, to stain the spores. The media were distilled water, peptonized 

 broth, gelatin, agar, and potato ; the dyes were methylen-blue, fuchsin, 

 and methylen-violet. Sterilization was performed in the usual way. 

 The results were as follows : — 



Distilled water and methylen-blue ; typhoid bacillus grow feebly, 

 but were stained, the water being unaffected. Similar results were 

 obtained with fuchsin, methyl-violet, and Bismarck brown. Peptonized 

 broth coloured as above becomes decolorized, but the bacilli are unaf- 

 fected. If the test-tube be shaken the colour returns. Stained with 

 fuchsin the broth gave similar results ; but with methyl-violet the 

 bacillus grows slowly, but is stained. Pneumonia coccus gave similar 

 results ; that is, it was stained with methylen-violet, but not with other 

 dyes. Anthrax seems to have stained in the blue-violet and red anilin 

 if the medium were deeply stained. On gelatin stained with methylen- 

 blue typhoid bacillus developed a colour, and this was demonstrated 

 microscopically. Bismarck brown and methyl-violet gave similar 

 results, but fuchsin failed. Pneumonia coccus only developed a faint 

 colour when the medium was highly charged with pigment. On agar 

 the typhoid bacillus is coloured with methylen-blue and methyl-violet, 

 but not with fuchsin. On potato, coloured with methylen-blue, typhoid 

 bacillus developed a hue much deeper than the cultivation medium ; but 

 there was no result with fuchsin. 



Nitrate of Silver Method.t — Sig. C. Martinotti proposes the follow- 

 ing improvements on the method of staining with nitrate of silver : — 

 (1) increase the volume of the silver solution in proportion to that of 

 the object to be stained; (2) increase the duration of immersion (15-30 

 days) ; (3) maintain the objects at a temperature of about 25 degrees 

 for ganglionic cells, or if for neuroglia cells alone at 35-40 degrees ; 



* Atti Soc. Tosc. Sci. Nat., vi. (1887) Proc. Verb., pp. 15-9. 

 t Arch. ItaL Biol., ix. (1887) pp. 24-5. 



z 2 



