ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 919 



dead tissues and for thin parts capable of ready examination by trans- 

 mitted ligbt. The stain recommended is Violet B. of Bindschedler 

 and Busch (Bale) in the proportion of one gramme to 300 c.c. of 

 ^ per cent, salt solution. 



The mesentery is very well stained by this reagent, the vascular 

 system being very clearly brought out, while the connective tissue is 

 rendered pale red ; this is best seen in one of the tdcJies laiteuses of 

 Kanvier. The piece should be first shaken up in a test-tube with some 

 ^ per cent, solution of common salt, then spread out smooth on a glass 

 plate with a brush, covered with a drop of staining fluid for ten to thirty 

 seconds, then removed with a bristle, washed with salt-solution, and 

 placed on a glass slip in salt-solution for examination. The method 

 is said to be preferable to injection, from the distinctness with which 

 the vessels are brought out, the definition of the structure of their 

 walls, the superior rapidity and simplicity, and the prevention of 

 misleading appearances. Specimens too deeply stained can be made 

 paler by washing in ^ per cent, salt solution ; specimens which are 

 quite fresh require a rather lengthy staining, viz. i to 1 minute. 

 Another very good object to which to apply the method is the hyaloid 

 membrane of the frog's eye. It is also useful in the study of fat-cells 

 in process of atrophy. Occasionally the contents of the cells are them- 

 selves stained. Certain cells, apparently plasmatic or food-cells, are 

 brought prominently into view in the mesentery, omentum, and liga- 

 mentum uteri of the rat by this method ; the granules may be coloured 

 violet or dark blue. 



It is especially useful for exhibiting smooth muscular fibres, as 

 found in tracts in the serous membranes of the pelvis, abdomen, and 

 thorax, and forming a netted layer in the peritoneum surrounding the 

 vas deferens and spermatic vessels ; also for elastic tissue, which may 

 thus be well seen in the meso-rectum of the rabbit ; also for the grey 

 nerve-fibres of the serous membranes of the frog, and for the larger 

 and smaller lymphatic vessels. No means have at present been 

 devised for rendering permanent preparations made in the above 

 manner. The two plates accompanying the paper contain some 

 beautiful figures of preparations made according to the method. 



Series Preparations.* — Almost the same considerations which led 

 Dr. Giesbrecht f to his method of mounting sections in series, gave 

 Dr. J. H. L. Flogel the idea four years ago, of using a substance for 

 fixing in which the imbedding mass is absolutely insoluble. For 

 this purpose he used an aqueous solution of gum arable for objects 

 imbedded in paraf&n. 



A filtered solution is prepared of 1 : 20, and, in order to protect it 

 from mould, a dash of alcohol is added. The slide must be so care- 

 fully cleaned that it can be evenly wetted all over. The gum solution 

 is poured over the whole surface of the slide and allowed to run off. 

 The process can then be carried on in two ways. Either the glass is 

 placed perpendicularly to dry, protected from dust, the sections 

 arranged on the dry surface, and breathed upon so strongly that the 



* Zool. Anzeig., vi. (1883) p. 565. 



t Ibid., iv. (1881) p. 484. Of. this Journal, i. (1881) p. 953. 



