736 SUMMARY or CURRENT RESEARCHES RELATING TO 



ture. After cooling an abundant quantity of naphtha oil is poured 

 over the preparation, and the liquid allowed to run off quickly until 

 the sections appear almost dry. Then, without any danger, the pre- 

 paration can be placed in absolute alcohol, staining fluid, water, &c., 

 in order to stain the sections and treat them further. Only when they 

 are very small is there danger of their being washed away. In order 

 to prevent this, spread over them, after the naphtha oil is almost all 

 evaporated, a few drops of guttapercha solution, allow it to dry, and 

 then place in alcohol, &c. The staining succeeds perfectly in this 

 case also, as the guttapercha has not time to penetrate into the tissues 

 but only covers the sections, without hindering the entrance of other 

 liquids. 



If, for any reason, the methods here given are not applicable, or 

 should the sections become detached, Dr. Frenzel uses another method 

 which, although longer than the preceding, has been of great service 

 to him. After the sections have been fixed according to Giesbrecht's 

 method, or with gum arabic, and the paraffin has been removed with 

 oil of turpentine, the latter is allowed to evaporate as much as pos- 

 sible, or is washed out with chloroform ; then a few drops of gutta- 

 percha solution are put upon the section, the fixing substance is 

 allowed to dry somewhat, and the preparation then placed in alcohol, 

 &c. This latter method is an absolutely certain one, although con- 

 siderably more lengthy than the previous one. 



The end of the process is the same in all cases, being that pre- 

 viously recommended by the author and later by Threlfall. 



Fixing and Staining Sections on the Slide.* — H. Schiillibaum, 

 finding that Giesbrecht's method will not allow of the staining of 

 the sections on the slide, at least when they are to be afterwards 

 mounted in balsam, suggests the use of a solution of nitro-cellulose 

 in oil of cloves. One part of collodion is mixed (according to its 

 consistence) with 3-4 volumes of oil of cloves or lavender oil, and well 

 shaken. The clear solution is spread with a brush over the slide in 

 a thin layer, which at ordinary temperatures remains fluid for a long 

 time, and adheres well. After the sections have been arranged, the oil 

 of cloves is evaporated by gentle heat over a water bath, which takes 

 5-10 minutes. The sections thus fixed can be treated for days with 

 oil of turpentine, chloi'oform, alcohol, and water, without losing their 

 adhesion. The subsequent staining is accomplished in the ordinary 

 manner. 



Sections from all imbedding masses known to the author can be 

 fixed in this way, and afterwards mounted in balsam or in glycerine. 

 Cloudiness may appear between the sections, through the solution 

 having been too concentrated and laid on too thick ; this may be re- 

 moved by passing a brush wetted with oil of cloves several times 

 between the sections. 



Freeing Objects from Air.f — A writer, whose name is not given, 

 describes the following very simple but efficient process for freeing 



* Arch. f. Mikr. Anat., xxii. (1883) pp. 689-90. 

 t Nature, xxviii. (1883) p. 322. 



