SYNTHETIC! REVIEW. 285 



the stain at once must be warmed over and over again. . 

 Clove oil must be avoided for clearing. 



BENDA'S copper haematoxylin stain may also be employed 

 (see below, 612). 



The staining of the achromatic figure, including the Neben- 

 kern, is another matter. These structures only stain in a 

 really distinct manner in two reagents, Kernschwarz and 

 hsematoxylin. I unhesitatingly recommend haematoxylin 

 (see below, 607). 



For a double-stain I recommend Rabl's combination of 

 hsematoxylin followed by safranin, if it be wished to demon- 

 strate the achromatic figure at the same time as the chromatic 

 element, This is the only combination known to me that will 

 do so in a really satisfactory way. One would think that 

 safranin and Kernschwarz might be better, but hitherto I 

 have not been able to succeed with this plausible combination. 



605. Mounting. For fresh objects you have so large a 

 choice of mounting media that you may take whatever liquid 

 gives you the best optical results. Sections of hardened tissue 

 should always (if possible) be mounted in damar (or colopho- 

 nium), not balsam, as the slightly lower index of damar or 

 colophonium solutions gives more powerful images of very 

 delicate details. If you have to deal with objects so delicate 

 that you have cause to fear mechanical injury to them on put- 

 ting them into damar, they may be mounted in thickened 

 turpentine (or cedar oil, but turpentine is preferable on ac- 

 count of its lower index) . Rabl has lately been using methyl 

 alcohol as an examination medium for dehydrated objects ; 

 but the preparations do not keep in this. Castor oil may be 

 tried (GRENACHER) ; I have not had good results with it. 



606. Synthetic Review. The following examples will serve 

 to gather up into one view the directions given in the preced- 

 ing paragraphs. 



FLEMMING'S Method may be stated as follows. Fix, for 

 twenty-four hours or more, in chromo-aceto-osmic acid or in 

 one of Rabl's liquids. Wash out in running water for an 

 hour or more. Bring the preparation into alcohol, and let 

 it remain in absolute alcohol for at least some hours. Then 

 imbed it by the method of simple imbedding, without penetra- 

 tion, in paraffin, in pith, or in celloidin, and make sections 



