278 SUilMART OF CUEEEyX KESEAECHES EELATDCa TO 



varnish " in 2 parts of pure benzole. Apply a drop or two of the 

 solution to a slide, and in a few seconds, or as soon as the varnish has 

 set, press the wing of the butterfly gently upon the slide, and then 

 carefully lift it away. The scales will be found transferred to the 

 slide in their beautiful natural arrangement * on the wing. Make a 

 shallow cell around the mounting and apply the cover-glass. Canada 

 balsam must not be used, as it disarranges the object. 



Imbedding Ctenophora.+ — For imbedding Ctenophora (for the 

 most part after hardening in osmic acid), E. Hertwig employs gum- 

 glycerine very largely diluted with water ; it is allowed to remain in 

 contact with the air, with the substance to be cut immersed in it, 

 until it has acquired the consistency of a stiff syrup. Shrinkage of 

 the gelatinous tissue is to some extent obviated by this plan, owing 

 to the slowness with which it absorbs the constantly thickenin_g gum- 

 glycerine. 



Staining Living Protoplasm with Bismarck Brown. t — L. F. 



Henneguy having treated Paramcecium aurelia with an aqueous solution 

 of aniline brown f known in commerce as "Bismarck brown"), was 

 surprised to see them assume a rather intense yellow brown colour, 

 and move rapidly about in the fluid. The colour first appeared in 

 the vacuoles of the protoplasm, and then it invaded the protoplasm 

 itself. The nucleus generally remains colourless, and thus becomes more 

 visible than in the normal state. Infusoria thus coloured were kept 

 for nearly fifteeu days. If a yellow-tinted ParamcEciura is wounded 

 or compressed so as to cause a small quantity of the protoplasm to 

 exude, it is seen that it is really the protoplasmic substance which is 

 coloured. All Infusoria may be equally stained vrith. Bismarck brown, 

 but no other aniline colours employed by the author exhibited the 

 same property, they only stained the Infusoria after death, and some 

 of them are in fact poisonous. 



As it is generally admitted that living protoplasm does not absorb 

 colouring matters, and that Infusoria are essentially composed of 

 protoplasm, M. Henneguy endeavoured to ascertain whether proto- 

 plasm in general, of animal or vegetable origin, behaved in the same 

 way in the presence of aniline brown. 



A tolerably strong dose of Bismarck brown was injected under the 

 skin of the back of several frogs. After some hours, the tissues were 

 uniformly tinted a deep yellow, the muscular substance especially 

 had a very marked yellow tint. The frogs did not appear in the 

 least incommoded. 



Small fry of trout placed in a solution stained rapidly and con- 

 tinued to swim about. 



Finally, a guinea pig, under whose skin some powder of Bismarck 

 brown had been introduced, soon presented a yellow staining of the 

 buccal and anal mucous membranes and of the skin. 



Seeds of cress sown on cotton soaked with a concentrated solution 



* It should be observed that tlie scales will have their under sides uppermost, 

 whicli is not the " natural arrangement." — Ed. 

 t Jen. Zeitschr., xiv. (1880) pp. 313-14. 

 X Rev. Intemat. Sci. Biol., viii. (1881) pp. 71-2. 



