G72 SUJI5IARY OF CURRENT RESEARCHES RELATING TO 



cast slips onsily out of tlio tube. According to its size and thickness 

 it is placed for 1-4-8 days in 1 per cent, bichromate of potash solution, 

 which nnist stand in the light so as to produce a modification of gelatin 

 insoluble in water. The gelatin is then carefully washed and hardened 

 in 70^ and OG"^ siiirit. "When the desired consistence has been attained 

 the gelatin cast is cut up longitiidinally or transversely into iiicccs, and 

 these are stuck with gum on cork, and then placed in absolute alcohijl 

 for ttt'enty-four hours. Before making sections it is advisable to remove 

 the external layer of gelatin, as it is too hard, and interferes with 

 manipulation. Drying, staining, decolorizing, and clearing up aro to 

 be carried out on the cover-glass. 

 For staining the author used — 



(1) Loffler's alkaline methylen-blue solution, but did not employ tho 

 1/2 per cent, acetic acid, and decolorized with the spirit. This usually 

 gave good results. 



(2) Watery methyl-violet solution (b B extra, Stuttgart Fabrik, Catal. 

 528) was not so useful, as although the bacteria were well stained, they 

 easily lost their colour. 



(3) Gentian-violet in watery solution was a failure, as it had some 

 solvent action on the gelatin. 



(4, 5) Bismarck brown and Babes's anilin safranin stained well, but 

 the decoloration of the gelatin was slow and rarely perfect. 



(6) Gram's and Weigert's method gave excellent results. Tho former 

 requires oil of cloves for decolorizing, as spirit alone is insufficient. 

 The decolorized sections should always be cleared up with bcrgamot oil. 



(7) Double staining with anilin methyl-violet, Bismarck brown, or 

 anilin fuchsin-mctliylcn blue did not produce favourable results. 



When decolorizing it is advisable to wash in water before using tho 

 spirit ; clearing up should be performed in bcrgamot oil, and the 

 specimen mounted in thickened balsiim. 



Though this method has the advantage of allowing spore-formation 

 to be observed under high powers, of showing the way in which the 

 individuals arc disposed, and even of disclosing impurities otherwise 

 unsuspected, it is not available for micro-organisms which fluidify gelatin. 



Agar cultivations were manipulated by stripping off small lumps of 

 the cultures and plunging them into agar liquefied at 40^, so that they 

 became imb(;dded when the agar set. The agar was removed from the 

 tube and hardened just as in the gelatin cultivations, but as it was not 

 susceptible of being sectioned, the pieces were saturated with bcrgamot 

 oil, then plunged into a mixture of paraffin and bergamot oil, and lastly 

 left in pure paraffin for twelve to twenty-four hours in an incubator. 

 W^hen cooled very fine sections can be made, and the process is then 

 reversed to rid them of the paraffin, and they are then treated like tho 

 gelatin sections. The staining is not so satisfactory as with the gelatin 

 method, but the photographic results are very good. A mixture of agar 

 and gelatin was also used by the author for certain organisms which 

 requii-e a firm medium. This method does not offer any other advan- 

 tage, as the microscopical appearances are deceptive and hardening an 

 impossibility. 



C A M p B E L L, D. H. — Paraffin-Einbettungs-Methode fiir pflanzliclie Objecte. (Paraffiu 

 imbedding method for vegetable objects.) 



Naticrwiss. Wochenschr., II. (1888) p. 61. 

 Rum IT I, G. — Presentazione di un Microtomo. (Exhibition of a microtome.) 



Atti Soc. Tosc. Sci. Nat. Pisa, V. (1888) pp. 2.")0-l. 



