70 DE-ALCOHOLISATION AND CLEARING 



139. Cinnamon (or Cassia) Oil greatly resembles clove oil, but is in 

 general thinner, and is more highly refractive. An excellent medium, 

 which we particularly recommend. 



140. Oil of Bergamot (Schiefferdecker, Arch. Anat. Phys., 

 1882 [Anat. Abth.], p. 206.) Clears 95 per cent, alcohol prepara- 

 tions and celloidin preparations quickly, and does not extract 

 anilin colours. 



Bergamot oil is the least refractive of these essences, having a lower 

 index than even oil of turpentine. 



SucHANNEK (Zcit. iviss. Mik., vii, 1890, p. 158) says that bleached, 

 colourless bergamot oil will not take up much water, whereas a green 

 oil will take up as much as 10 per cent. 



Van der Stricht (Arch, de Boil., xii, 1892, p. 741) says that bergamot 

 oil will, with time, dissolve out the fatty granules of certain ova. 



141. Oil of Origanum (Neelsen and Schiefferdecker, Arch. Anat. 

 Phys., 1882, p. 204). Ninety-five per cent, alcohol preparations are 

 cleared quickly, and so are celloidin sections, without solution of the 

 celloidin. Anilin colours are somewhat extracted. 



For work with celloidin sections care should be taken to obtain 01. 

 Origani Cretici (" Spanisches Hopfenol "), not 01. Orig. Gallici (v. 

 GiESON ; see Zeit. wiss. Mik., iv, 1887, p. 482). Specimens of origanum 

 oil vary greatly in their action on celloidin sections. 



Squire, in the Methods and Formulce, etc., p. 81, says that origanum 

 oil (meaning the commercial product) is nothing but oil of white thyme 

 more or less adulterated (see next §), and that the product sold as 01. 

 Origani Cretici is probably oil of marjoram. 



142. Oil of Thyme. Fish {Proc. Amer. Mic. Soc, 1893 ; Zeit. wiss. 

 Mik., xi, p. 503), following Bumpus, says that for most of the purposes 

 for which origanum oil has been recommended, oil of thyme will do just 

 as well if not better. The red oil is just as sufficient as the white for 

 clearing. 



Schimmel & Co., in their Report of October, 1895, p. 69, state that 

 in France white oil of thyme is adulterated with oil of turpentine to the 

 extent of as much as 50 per cent. 



143. Oil of Gaultheria. Used by Unna (Monatschr. prakt. Derm., 

 Erganzungsh., 1885, p. 53) for thinning balsam. The artificial oil, 

 methyl salicylate, is recommended by Gueguen (Comj). Rend. Soc. 

 Biol., v, 1898, p. 285) both as a de-alcoholisation and clearing agent and 

 as a solvent of paraffin. The refractive index is 1*53. It is, unfortu- 

 nately, easily spoilt by water. 



144. Sandal-wood Oil (Neelsen and Schiefferdecker, loc. cit.). 

 Very useful, but its high price is prohibitive. 



145. Oil of Cajeput. See last edition. 



146. Oil of Turpentine. Generally used for dissolving out the paraffin 

 from sections ; but many other reagents, such as xylol and benzol, 

 are preferable for this purpose. If used for alcohol objects, it causes 

 considerable shrinkage, and alters the structure of cells more than any 

 other clearing agent known to me. Turpentine has the lowest index 

 of refraction of all the usual clearing agents except bergamot oil ; it 

 clears objects less than balsam. (See under " Cytology," § 710.) 



147. Terpineol (liquid, from Schimmel «& Co.) is recommended 

 by Mayer, Zeit. wiss. Mikr., xxvi, 1910, p. 523. Clears from 



