HARDWICKE'S SCIENCE-GOSSIP. 



49 



NOTE ON PREPARING AND PRESERVING DELICATE 



ORGANISMS.* 



T will not do to rely 

 on the chemists 

 and druggists of 

 the south of France 

 or the Italian coast 

 for the chemicals 

 requisite for re- 

 searches in the 

 natural history of 

 those parts. If you 

 go to these worthy 

 folk and ask for 

 what you want, . 

 they will stare at 

 you and ask if you 

 are a doctor, or 

 what you intend 

 to do. If you ex- 

 plain, they will 

 gaze at you in as- 

 tonishment, and 

 perhaps ask to see your papers, and you will be lucky 

 if they do not denounce you to the police ! It is 

 therefore necessary to carry all requisites with one. 

 But liquid chemicals are bulky, and leaky bottles 

 may stain the contents of the portmanteau ; besides 

 which the stock is soon exhausted. Crystalline sub- 

 stances, on the other hand, are easily conveyed, and 

 contain in small bulk enough material to prepare and 

 preserve a large number of objects. 



The beautiful orange crystals of bichromate of 

 potash form a very suitable solution for histological 

 researches and for the preservation of delicate organ- 

 isms. A few grammes of this salt, portable in any 

 box, will meet all requirements. It dissolves in fresh 

 or salt water, a few crystals saturating a large bulk. 

 In this solution all the lower gelatinous animals, such 

 as polypes, Hydromedusce, Medusae, Salpae, cteno- 

 phora, &c, can be perfectly preserved. The shell- 

 less mollusca and annelids, and all worms with tough 

 skin can be kept in it. Small Crustacea and bryozoa 

 give also excellent results. We have kept a splendid 

 Jl r cdusa aarita in this way for a whole year, and its 

 No. 171. 



beauty and transparency leave nothing to be desired. 

 But this solution has one inconvenience, it permits 

 the development of mould ; but this can be prevented 

 by the addition of a few drops of phenic acid or 

 phenic alcohol. 



For histological purposes it is as good as, but acts 

 more delicately than chromic acid. It hardens the 

 tissues, brings out the outlines of the cellules, shows 

 their nuclei, and coagulates the sarcode. It is also 

 a valuable agent in maceration, dissolving in most 

 cases the intercellular cement and separating the parts. 

 On this account only tough-skinned organisms can be 

 preserved in it, lest the tissues fall to pieces. Still 

 the most delicate parts of the vibratile cilia and 

 infusoria are well preserved. 



Another convenient and portable salt is perman- 

 ganate of potash, a little of which goes a long way. 

 It is especially good in histological researches, as it 

 acts like osmic acid, burning up the protoplasm, 

 bringing out the minutiae, and showing the nuclei 

 outlines of cells, &c. It is used as a saturated solution 

 in distilled or very pure spring water. Sea- water also 

 dissolves it. The concentrated solution, of a lovely 

 violet colour, kills small organisms at once, and then 

 burns them. They are left in it from thirty minutes 

 to an hour, then withdrawn and placed in alcohol, 

 after which they can be made transparent with essence 

 of terebinth and mounted in Canada balsam. Beau- 

 tiful results are thus obtained with echinoderms, 

 zoophytes, worms, and marine arthropoda. For 

 delicate researches, especially in the ciliated infusoria, 

 it is better than osmic acid) without its great cost, 

 and is everywhere easily obtained. G. du P. 



Note by Translator. — Permanganate being deli- 

 quescent, and both salts highly coloured, wide-mouthed 

 bottles will be found the best mode of conveyance ; 

 the corks being coated inside with beeswax or other 

 protecting substance. The prices of the salts are, 

 bichromate, is. tyi. per lb., and permanganate, S</. 

 per oz. W. H. D. 



* By G. du Flessis, in " Bulletin de la Societe Vaudoise des 

 Sciences Naturelles," ser. 2, vol. xv. pp. 278-280, April 1878. 

 Translated by W. H. Dalton. 



D 



