FEET'S WHITE GELATIN MASS. 229 



the injection mass may be mixed in less than a quarter of an 

 hour. Its advantages are that, on account of the extremely 

 fine state of division of the precipitate, the mass is almost 

 transparent, and runs so freely that even lymphatics may be 

 perfectly injected with it, whilst its intensity of colour makes 

 the vessels much more distinct than the very pale mass of 

 Thiersch (No. 456). It is also easier to manage than 

 Thiersch's mass, as it does not solidify so quickly. It shows 

 well in the vessels by reflected, as well as by transmitted, 

 light. 



458. Fol's Lead Chromate Gelatin Mass (Lehrb., p. 15). 



459. Hover's Silver Nitrate Yellow Gelatin Mass (Biol. Gen- 

 fraZR,ii,1882,pp. 19,22; Journ.Roy.Mic.Soc.{N.S.), iii, 1883, 

 p. 142 j. " A concentrated solution of gelatin is mixed with an 

 equal volume of a 4 per cent, solution of nitrate of silver and 

 warmed. To this is added a very small quantity of an aqueous 

 solution of pyrogallic acid, which reduces the silver in a few 

 seconds ; chloral and glycerin are added as before " (see ante, 

 HOYER'S formula for carmine gelatin, No. 445). 



This mass is yellow in the capillaries and brown in the 

 larger vessels. It does not change either in alcohol, chromic 

 or acetic acid, or bichromate of potash, &c. 



460. Hover's Green Gelatin Masses (Ibid.). Made by mixing 

 a blue mass and a yellow mass. 



461. Thiersch's Green Gelatin Mass (Arch. f. mik. Anat., 1865, 

 p. 149). Made by mixing the blue mass, 452, and the yellow 

 mass, 456. 



462. Robin's Scheele's Green Gelatin Mass (see 438). 



463. Hartig's White Gelatin Mass (FREY, Le Microcope, p. 

 190). Dissolve 125 grammes of acetate of lead in so much 

 water that the whole shall weigh 500 grammes. 



Dissolve 95 grammes of carbonate of soda in so much water 

 that the whole shall weigh 500 grammes. 



Take equal volumes of the two solutions, and add two 

 volumes of gelatin solution. 



464. Frey's White Gelatin Mass (Ibid). Put into a tall glass 

 cylinder 125 to 185 grammes of cold saturated solution of 



