206 EXAMINATION AND PRESERVATION MEDIA. 



previously soaked for some time in a small bottle of the 

 medium warmed with a suitable apparatus. 



390. Kaiser's Glycerin Jelly (Bot. Cent., i, 1880, p. 25; 

 Journ. Roy. Mic. Soc., in, 1880, p. 504). One part by weight 

 finest French gelatin is left for two hours in 6 parts by weight 

 distilled water, 7 parts of glycerin are added, and for every 

 100 grammes of the mixture 1 gramme of concentrated 

 carbolic acid. Warm for ten to fifteen minutes, stirring all 

 the while, until the whole of the flakes produced by the carbolic 

 acid have disappeared. Filter whilst warm through the finest 

 spun glass laid wet in the filter. Use for mounting as above. 



I prepared some of this jelly many years ago, and find it is 

 still perfectly clear. 



391. Seaman's Glycerin Jelly (Amer. Mon. Mic. Journ., ii, 

 1881, pp. 45; Journ. Roy. Mic. Soc. (N.S.), i, 1881, p. 534). 

 Dissolve isinglass in water, so that it makes a stiff jelly 

 when at the ordinary temperature of the room, add one tenth 

 as much glycerin, and a little solution of borax, carbolic acid, 

 or camphor water. Filter whilst warm through muslin, and 

 add a little alcohol. 



392. Pol's Glycerin JeUies (Lehrb., p. 138). 



1. Melt together 1 volume of Beale's jelly ( 388) and one 

 half to 1 volume of water, and add 2 to 5 per cent, of salicylic 

 acid solution, or carbolic acid or camphor. 



2. Gelatin 30 parts. 



Water 70 



Glycerin 100 



Alcoholic solution of camphor . . 5 



Prepare as before, adding the camphor last. 



3. Gelatin 20 



Water 150 



Glycerin . .100 



Alcoholic solution of camphor . . 15 



393. Castor Oil. This has been lately recommended as a mounting 

 medium for certain delicate tissues (sections of eyes of Cephalopoda) by 

 ORENACHEH (Abhandl. naturf. Ges. Halle-a.-S., Bd. xvi ; Zeit.f. wiss. Mik., 

 1885, p. 244). This was with the idea that its low refractive index (n = 

 1/49, whilst Canada balsam n =1'54) would give a useful augmentation of 

 visibility for the more refractive elements of the tissues. 



