704 SUMMARY OF CURRENT RESEARCHES RELATING TO 



We owe another preparation to Kaiser,* He leaves for two hours 

 1 part by weight of French gelatin in 6 parts of distilled water ; he 

 afterwards adds 7 parts of pure glycerin ; and into 100 gr. of the 

 mixture he introduces 1 gr. of carbolic acid. He heats and shakes 

 the whole for ten or fifteen minutes, until it becomes fluid and clear, 

 after which he filters it. 



This glycerin jelly in a thin film has the clearness and trans- 

 parency of water. It is useful for all those preparations which, 

 requiring a cover-glass, are yet so delicate that the cover injures 

 them; such as pollen-grains, starch-grains, feculas, yeast-cells, and 

 spores, especially those of nnicellnlar algte like Desmidiete. 



The same liquid is excellent for preserving the structure of the 

 protoplasm and the distribution of the chlorophyll-bodies whose 

 form and position have been fixed by absolute alcohol or osmic acid. 

 When the preparation has been thus fixed it is put into dilute glyce- 

 rin, then into the glycerin jelly. After this liquid has become cold, 

 the cover-glass can be luted. 



Canada Balsam, by reason of the difference of the refractive 

 powers, is prefei-able for the preservation of diatoms ; it is liquefied 

 by warming. " The finest stria3 on the diatoms are visible in it." 



A very concentrated solution of balsam in ether or chloroform can 

 be substituted for pure balsam ; this mixture is purer. Delicate 

 objects which contain much water do not keep well in balsam until 

 they have been dried in the air, or treated with absolute alcohol or oil 

 of cloves. 



All the preparations, even those in balsam, should be luted. 



Rapid Method of Demonstrating the Tubercle Bacillus without 

 the use of Nitric Acid.! — The following method, which Dr. H. 

 Gibbes has used for some time with great success, will, he thinks, 

 prove useful to those requiring the demonstration of the tubercle 

 bacillus for diagnostic purposes in a rapid manner. The great advan- 

 tage consists in doing away with the use of nitric acid. 



The stain is made as follows : — Take of rfisanilin hydrochloride two 

 grammes, methyl-blue one gramme ; rub them up in a glass mortar. 

 Then dissolve anilin oil 3 c.c. in rectified spirit 15 c.c. ; add the 

 spirit slowly to the stains until all is dissolved, then slowly add dis- 

 tilled water 15 c.c, ; keep in a stoppered bottle. 



To use the stain :^The sputum having been dried on the cover- 

 glass in the usual manner, a few drops of the stain are poui-ed into a 

 test-tube and warmed ; as soon as steam rises pour into a watch-glass, 

 and place the cover- glass on the stain. Allow it to remain for four 

 or five minutes, then wash in methylated spirit until no more colour 

 comes away ; drain thoroughly and dry, either in the air or over a 

 spirit-lamp. Mount in Canada balsam. The whole process, after the 

 sputum is dried, need not take more than six or seven minutes. This 

 process is also valuable for sections of tissue containing bacilli, as 



* Bot. Centralbl., 1880, p. 25. Cf. 'Glycerin- gelatine for Mounting,' this 

 Journal, iii. (1880) p. 502. 

 t Lancet, i. (1883) p. 771. 



