464 NOTES AND MEMORANDA. 



The picro-carmine does not sensibly colour Bacteria, but it 

 colours very clearly the nuclear formations contained in the bodies of 

 the Infusoria. After the colouring glycerine can be added, and the 

 preparation is complete. 



In the study of the lower vegetable forms with naked protoplasm, 

 Myxomycetes, for instance, osmic acid and picro-carmine and hema- 

 toxylin can be equally well used. By the action of osmic acid the 

 currents in the protoj)lasm of the Myxomycetes are instantly sus- 

 pended, and in a few instants the protoplasm is sufficiently hardened 

 to make sections possible. 



There are certain exceptional cases in which osmic acid has no 

 direct action. A Nematode, for instance, Anguillula aceti, can live a 

 long time in a liquid containing osmic acid. In the case of a female 

 the eggs develop and hatch, and the embryos grow at the expense of 

 the mother, until nothing remains of her body but the outer cuticle, 

 which resists all attacks of the acid. When the young Anguillulte 

 have piei'ced the cuticle and are free, they swim apparently unharmed 

 by the acid, though they generally die in a few days. 



A similar example is furnished by the larvae of the Diptera, 

 CMronomns plumosus Linn., which lives in water strongly mixed with 

 osmic acid, owing to its cuticle resisting the acid. 



Another Method of Preserving Bacteria, &c. — " T. C," in 

 ' Science-Gossip,'* says that he has experimented upon a method for 

 obtaining permanent preparations of Bacteria, Vibriones, &c., and after 

 some years of patient research has found the following excellent 

 method : — The requisites are a bottle of thin Canada balsam diluted 

 with chloroform, a hot-water plate, and the fixing solution, which 

 consists of 25 cc. of chromic oxidichloride acid to which is added 

 50 cc. of water with 50 cc. permanganate of potash. A ring of white wax, 

 much larger than the cover-glass, is drawn on the slide, within which 

 the organisms are placed with some water. When they have attached 

 themselves to the slide, some of the solution is added, which will 

 instantly fix the specimen. After three minutes the w^ater may be 

 poured out, and a few drops of chloroform added and poured ofl', the 

 cover-glass placed carefully on, and a few drops of dilute Canada 

 balsam added, so as to flow i;nder the cover, and the preparations 

 placed on the hot-water plate to dry. Thus prepared they retain all 

 the features of the living animal. 



Mounting Noctiluca miliaris. — Some Noctilucce having been col- 

 lected last summer in Beaumaris Bay, Mr. J. E. Lord says | that he 

 and Dr. Worrall tried mounting them in shallow cells, with various 

 preservative media to compare the results. Balsam, glycerine, fresh 

 and sea-water, glycerine jelly. Dean's medium, and several others 

 were tried. One or two of the slides rapidly deteriorated, others held 

 out for a longer period, but the specimens mounted in sea-water 

 retained all their features to this date (not siiecified). As the animals 

 retain their shape, it would appear that there has been no endosmose 

 or exosmose action going on. 



* ' Sci.-Gossip,' 1879, No. 173, p. 111. t Ibid, p. 113. 



