ZOOLOGICAL STATION IN NAPLES. 229 



warmed, and the shellac surface washed with oil of cloves for the 

 purpose of softening it. The wash is made with a small brush 

 drawn back and forth until the entire surface has been moderately 

 but evenly wet with the oil. Sections are now cut and arranged 

 for the first cover ; this done, the slide is warmed over a spirit- 

 lamp so that the paraffine adhering to the sections melts and flows 

 together, forming an even layer, which cools almost instantly, and 

 thus secures the position of the sections, while those of the second 

 cover are prepared. The sections for the last cover having been 

 completed, the slide is warmed for ten minutes on a water bath, 

 in order that the sections may sink into the shellac and become 

 fixed, and the clove-oil evaporate. After allowing the slide to 

 cool, the process is concluded by washing away the paraffine with 

 turpentine, and inclosing in balsam dissolved in chloroform. 



VII. — Gaule's Method, 



Since the above was written, my attention has been called to 

 the following mode of fixing sections, first desciibed by Dr. Gaule : * 



I. — Sections cut dry and placed on the slide in the order and 

 position in which they are to be mounted. 



2. — They are then smoothed out by the aid of a fine brush 

 wet in 50-60 per cent, alcohol, until all wrinkles are removed and 

 every part is in close contact with the slide. 



3. — Slide allowed to stand several hours (or over-night) until 

 the alcohol has completely evaporated, and the sections are left 

 adhering quite firmly to the glass. The process may be hastened 

 by gently warming to 45-50^ C. 



4. — The paraffine may be removed by any of the solvents in 

 common use, but Dr. Gaule recommends Xylol. A few drops are 

 allowed to flow over the sections, and after a few moments the 

 paraffine is fully dissolved. 



5. — The balsam (a mixture of balsam and xylol in equal parts) 

 is placed on the cover-glass, and this allowed to sink slowly, from 

 one side, over the sections. 



Dr. Gaule finds it convenient, especially with serial sections, to 

 use large cover-glasses — often nearly as large as the slide itself. 

 Thus a single slide may often contain a large number of sections 

 closely arranged under one cover. 



* Archiv. f. Anat. u. Phys., 1881, Phys. Abthlg., p. 156, 



