ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1053 



remove all trace of the decolorizer, the incomplete removal of which 

 causes the stain to fade sooner or later. 



The edges of the collodion are next clipped off close to the preparation 

 and the slide dehydrated in strong spirit. It is then immersed in oil of 

 cloves, wherein it is almost instantaneously clarified. This done, the 

 surface is washed with xylol, and finally mounted in a mixture of gum- 

 dammar and gum mastic dissolved in xylol, and placed in a warm 

 chamber for twenty-four hours. 



Staining of Elastic Fibres witli Chromic Acid and Safranin.* — 

 Dr. L. Ferria, who has been examining various examples of safranin, 18 

 in all, found that these differed in colour, specific gravity, in their solu- 

 bility in water and spirit, and in their behaviour with chromic acid. 



"When an aqueous solution of chromic acid is added to an aqueous 

 solution of safranin a precipitate is thrown down. This precipitate may 

 vary from an abundant red, almost black, to a scanty red or yellowish 

 red, and it is the samples of the latter which are least satisfactory in 

 staining the elastic fibres. These latter were certified by their makers 

 to be the purer varieties, and the author notes also that those varieties 

 which stained elastic tissues well were less suitable for staining nuclei 

 or showing the nuclear mitosis. 



The author also found that preparations which had been hardened in 

 spirit were stained very well if the sections were left for about five hours 

 in a watery solution of safranin (1 : 1000) at a temperature of about 37°, 

 and then, having been washed, were placed in the safranin solution. If 

 the specimen should be overstained so that the section is of a diffuse 

 red colour, it should be treated for a short time with a very dilute 

 alcoholic solution of caustic potash and then left for 24 hours in 

 absolute alcohol. Only the nuclei of the tissue are then stained red, and 

 contrast well with the blackness of the elastic fibres. 



Clarifying in bergamot oil and mounting in dammar is said to aid 

 the clearness of the picture. 



Congo-red as a Reagent for Cellulose. t — Dr. E, Heiaricher in 

 examining the behaviour of Congo-red towards the thickenings in cell- 

 walls which occur as reserve matter in the cotyledons of Impatiens Bal- 

 samina and other varieties of Impatiens, found that these thickenings were 

 stained red. As another series of reactions negatived the cellulose nature 

 of these thickenings, the author proceeded to examine the behaviour of 

 this pigment towards the mucous element of plants. The general result 

 was that Congo-red stains not only cellulose ,nd amyloid matter, but 

 also mucus of most of the plants examined. 



Hence, the author concludes that Congo-red is not to be considered 

 as a specific reagent for cellulose, and, if used for distinguishing it, 

 great care must be taken to guard against errors. 



Simple and rapid Staining of the Tubercle Bacillus.:}: — Mr. H. P. 

 Loomis recommends Ziehl's solution for staining the tubercle bacillus, 

 and Fraenkel's methylen-blue solution as a contrast stain. This method 

 has the merit of being simple and rapid and dispensing with the use of 

 acids. 



* Zeitschr. f. Wiss. Mikr., v. (1888) pp. 341-3. 

 t Ibid., pp. 343-6. 



X Medical Record, xxxiii. (1888) p. 631. 

 1888. 4 B 



