EXAMINATION AND PRESERVATION MEDIA. 287 



447. Castor Oil. This was recommended as a mounting medium for 

 certain delicate tissues (sections of eyes of Cephalopods) by GBENACHEK 

 (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 (11 = T49, 

 whilst Canada balsam n = 1'54) would give a useful augmentation of visi- 

 bility for the more refractive elements of the tissues. 



With the objects with which I have experimented I have not had good 

 results. 



448. Photographic Negative Varnish (for mounting large sections 

 without cover-glasses). See WEIGEET, Zeit.f. wiss. Mik., iv, 2, 1887, p. 209. 



449. Styrax and Liquidambar. See Journ. Roy. Mic. Soc., 1883, 

 p. 741; ib., 1884, pp. 318, 475, 655, and 827; and the places there quoted. 

 Also Bull. Soc. Beige de Mic., 1884, p. 178; and FOL, Lehrb., p. 141. 

 These are very highly refractive media, which is just what is not wanted in 

 general in histology. 



450. Sandarac (LAVDOWSKY, from Ref. Handbook Med. Sci., Supp., 

 p. 438). Gum sandarac 30 grs., absolute alcohol 50 c.c. This may, if 

 desired, be diluted with an equal volume of absolute alcohol, and used for 

 clearing sections. 



450a. Gum Thus, dissolved in xylol, is recommended by EISEN, Zeit. 

 f. wiss. Mik., xiv, 1897, p. 201. 



