222 EXAMINATION AND PRESERVATION MEDIA. 



somewhat in it). The index of refraction is somewhat higher than that 

 of glycerin. Objects may be brought into it out of water. 



428. AMANN'S Lactophenol (from LANGERON, C. R. Soc. BioL, 

 Iviii, 1905, p. 750). Carbolic acid, 20 ; lactic acid, 20 ; glycerin, 40 ; 

 water, 20. For Nematodes, Acarids, etc. Add gradually drop by 

 drop to the water containing the organisms. Not for mounting. 

 Mount in glycerin jelly. 



Glycerin Media. 



429. Glycerin. Glycerin diluted with water is frequently em- 

 ployed as an examination and mounting medium. Dilution with 

 water is sometimes advisable on account of the increased visibility 

 that it gives to many structures. But for efficacious preservation 

 undiluted glycerin, the strongest that can be procured, should be 

 used (see BE ALE, How to work, etc.). 



For closing glycerin mounts, the edges of the cover should first 

 (after having been cleansed as far as possible from superfluous 

 glycerin) be painted with a layer of glycerin jelly ; as soon as this is 

 set a coat of any of the usual cements may be applied. See next 

 chapter. 



Glycerin dissolves carbonate of lime, and is therefore to be rejected 

 in the preparation of calcareous structures that it is wished to 

 preserve. 



430. Extra-refractive Glycerin. The already high index of refraction 

 of glycerin (Price's glycerin, n 1-46) may be raised by dissolving 

 suitable substances in it. Thus the refractive index of a solution of 

 chloride of cadmium (CdCl 2 ) in glycerin may be 1 -504 ; that of a 

 saturated solution of sulphocarbolate of zinc in glycerin may be 1 -501 ; 

 that of a saturated solution of SCHERING'S chloral hydrate (in crusts) in 

 glycerin is 1-510 ; that of iodate of zinc in glycerin may be brought up 

 to 1 -56. For further details see previous editions, or Journ. Roy. Mic. 

 Soc., ii, 1879, p. 346 ; iii, 1880, p. 1051 ; (N.S.), i, 1881, pp. 943 and 366. 



431. Glycerin and Alcohol Mixtures. These afford one of the 

 best means of bringing delicate objects gradually from weak into 

 strong glycerin. The object is mounted in a drop of the liquid, and 

 left for a few hours or days, the mount not being closed. By the 

 evaporation of the alcohol the liquid gradually increases in density, 

 and after some time the mount may be closed, or the object brought 

 into pure glycerin or glycerin jelly. 



1. CALBERLA'S LIQUID (Zeit. wiss. Zool, xxx, 1878, p. 442). 

 Glycerin 1 part, alcohol 2, water 3. 



2. I strongly recommend the following for very delicate objects : 

 Glycerin 1 part, alcohol 1, water 2. 



