ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 279 



of the Bismarck brown sprouted, and tlie young plants were strongly 

 stained brown ; but on crushing the tissues and examining them under 

 the Microscope it was ascertained that the protoplasm of the cells 

 was very feebly coloured ; the vessels on the contrary showed a very 

 deep brown staining up to their termination in the leaves. 



The mycelium of a mould which had been developed in a solution 

 of Bismarck brown, was clearly stained after having been washed 

 in water, whilst it is known that the mycelium which frequently 

 forms in coloured solutions, picrocarmine, hgematoxylin, &c., remains 

 perfectly colourless. 



Other aniline colours injected under the skin of frogs stained the 

 fundamental substance of the connective tissue as deeply as did the 

 Bismarck brown ; but the cells of the muscular substance remained 

 perfectly colourless. 



The author concludes therefore that Bismarck brown possesses- 

 the property of colouring living protoplasm both in plants and 

 animals. 



Preservation of Infusoria and other Microscopical Organisms.* 

 — A. Certes, in a note supplementary to his previous communications,! 

 says that five years' experience has only confirmed his view of the 

 efficacy of osmic acid and iodized serum for preparing Infusoria ; but 

 sometimes, notwithstanding precautions, the animalcules become black 

 and opaque from a too prolonged action of the osmic acid ; or, 

 especially when iodized serum or lemon juice has been employed as 

 a fixing reagent, mouldiness attacks the preparations either because 

 the bottles have been badly corked or precautions for excluding germs 

 from the preparations have been neglected. 



It will be found however that ammonia (^) will clear prepara- 

 tions blackened by osmic acid, and thus the always dangerous use of 

 cyanide of potassium will be avoided ; but it is necessary to watch the 

 operation with care, the time of immersion in ammonia being 

 essentially variable according to the thickness of the animalcules and 

 the quantity of osmic acid in excess. 



With regard to mouldiness, it is possible, with certain precautions, 

 to filter the liquid which holds the altered gatherings in suspension, 

 upon pure glycerine. To increase the hardening of the animalcules, the 

 liquid in excess is first removed and replaced by strong alcohol, by 

 picrocarmine, or by green picrate of methyl, it is then poured gently 

 on the glycerine, which, owing to its density, remains at the bottom 

 of the vessel, but previously the liquid to be filtered must be briskly 

 agitated so as to disengage the animalcules cauglit by their cilia in 

 the matted fibres of the moulds. 



The Infusoria thus detached fall first to the bottom. The 

 patches of mycelium which olfer more surface and consequently more 

 resistance do not sink, or sink much more slowly. Advantage is 

 taken of this circumstance to decant the liquid with a pipette, and to 

 collect from the bottom of the vessel the Infusoria which, being 

 isolated, are best adapted for observation. 



* Bull. Soc. Zool. France, vi. (1881) pp. 36-37. 



t See tliis Journal, ii. (1879) p. 331 ; iii. (1880) p. 847. 



