264 INJECTIONS. 



solution made by adding a trace of dilute sulphuric acid to 

 " liqueur orange No. 3" (a liquid found in commerce, and 

 used for detecting acids) ; the solution takes on a gooseberry- 

 red colour. 



The preparation of the injection mass is facilitated by em- 

 ploying acetic acid and ammonia of known strength. For the 

 acetic acid it is sufficient to keep the glacial acid in a well- 

 stoppered bottle. But this will not suffice for the ammonia, 

 which is notably lowered in strength through the mere pour- 

 ing from one bottle into another. Ville has imagined an ap- 

 paratus which allows of withdrawing a known quantity 

 without permitting any access of air to the stock solution. 

 Description and figures, 1. c. 



With the exception of the processes above described, Ville 

 prepares the injection mass exactly as Ranvier. 



468. Gerlach's Carmine-Gelatin Mass (see Arch. f. mik. Anat., 

 1865, p. 148; and Ranvier's Traite, p. 113). 



469. Thiersch's Carmine-Gelatin Mass (see ibid.). 



470. Carter's Carmine-Gelatin Mass (see BEALE, p. 113). 



471. Davies' Carmine-Gelatin Mass (see his Prep, and Mount- 

 ing of Mic. Objects, p. ]38). 



472. Hoyer's Carmine-Gelatin Mass (Biol. Centralb., 1882, 

 p. 21). Take a concentrated gelatin solution and add to it a 

 corresponding quantity of neutral carmine staining solution 

 (see 163). Digest in a water-bath until the dark violet-red 

 colour begins to pass into a bright red tint. Then add 5 10 

 per cent, by volumes of glycerin, and at least 2 per cent, 

 by weight of chloral, in a concentrated solution. After 

 passing through flannel it can be kept in an open vessel 

 under a bell-glass. 



473. Fol's Carmine-Gelatin Mass (Zeit.f. wiss. ZooL, xxxviii, 

 1883, p. 492). 



The following method of preparation has the advantage of 

 producing masses that can be kept in the dry state for an 

 indefinite length of time. (Fol finds that the addition of 

 chloral hydrate to wet masses is not an efficient preservative.) 



One kilog. of Simeon's photographic gelatin* is soaked for 



* This gelatin may be obtained either from the ordinary furnishers of 



