780 Methods of Microscopical Research [October, 



at once removed from the alcohol, otherwise the color will be too 

 much weakened. If it be required to examine the objects before 

 mounting, they may be removed to distilled water, in which the 

 color of the nuclei will remain unchanged for a considerable time. 

 They must then pass through alcohol again before mounting. 

 5. Clarified in clove oil and mounted in dammar-lac} 



Clove oil withdraws the color a little, and hence it must not be allowed to work 

 too long. Creosote extracts the color still more rapidly than clove oil. 



B. Eggs of Eckinodermsr—ln his recent researches on karyo- 

 kinesis, Flemming states (p. 5) that he obtained serviceable stain- 

 ing of nuclei in the following ways : 



1. Living eggs colored on the slide, either with safranin or aniline 

 dyes, followed by acetic acid (1 percent.) which is allowed to flow 

 under the cover and thus replace the staining medium, or with 



Acetic acid carmine (after Schneider), used undiluted. The last 

 mentioned staining agent causes swelling, but still gives the typi- 

 cal features of the karyokinetic figures. 



2. Eggs first hardened in strong nitric acid (40-50 to aq. dest. 

 60-50), then washed in distilled water until the yellowish color, 

 due to the presence of the acid, disappears. Colored with acetic 



III. Methods of Dissecting. 



For the dissection of single organs, fresh animals arc generally 

 placed in dilute alcohol, or a weak chromic solution. Hut the 

 tissues are liable to suffer from maceration in these fluids, and 

 hence, where it is important that the tissues should be well pre- 

 served, it is advisable to use picro-sulphuric acid, regardless of 

 the injurious effects of the same on the dissecting instruments. 

 The hardening capacity of the picro-sulphuric acid is extremely 

 slight, but may be strengthened by the addition of chromic acid. 

 Preparations thus obtained, and subsequently treated with alco- 

 hol, staining fluids, &c, should be transferred to creosote for fur- 

 ther dissection, as the transparency induced by this medium will 

 greatly facilitate the work. 



IV. Imbedding. 



For section cutting, objects are usually imbedded in paraffine. 

 By low temperature, as in winter, it is necessary to work with a 

 softer paraffine than is required for summer. Instead of solten- 



1 Probably balsam dissolved in chloroform would answer the same purpose. 

 •Flemming. " Beitrage -.:ir Ken tm^ le Z He und ihrer Lebenserscheinungen. 



