ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 655 



95 per cent, alcohol to completely anliydrate the sections. They are 

 cleared with a mixture of carbolic acid 1 part, turpentine 4 parts. 

 The balsam to be used is j)repared by mixing 25 gr. of pure Canada 

 balsam with 2 cc. of chloroform and 2 cc. of olive oil. The latter 

 very soon removes any cloudiness that may have appeared in the 

 collodion film." 



Piffard's Slides. — Mr. B. Piflfard has patented a slide which is 

 made by forming with a diamond a round recess in an ordinary 

 slide. In this the object is placed, and covered with thin glass. The 

 upper surface of the slide is thus perfectly smooth, the cover-glass 

 being even with the slide. There is no danger of the cover-glass 

 and object being knocked off ; and the recess causes a very beautiful 

 diffusion of light. 



Mounting in Balsam in Cells.* — E. P. H. Durkee describes the 

 following process : — A curtain-ring, flattened by pressure, is placed 

 upon a clean slide and the slide placed on the hot table. Droj) in 

 the centre a small portion of balsam, enough to fill the cell, and heat 

 till the air-bubbles rise and permit of breaking with the needle ; at 

 the same time gently moving the ring about, and pressing it down to 

 insure contact with the slide. Place the object in the balsam, 

 taking care to see that it is completely covered ; warm the cover and 

 place it in position, in doing so holding it in the forceps parallel 

 with the surface of the slide, so as to expel the air all round. Weight 

 down with a bullet, and apply heat as may be necessary to harden 

 the balsam. 



What the author considers a feature is that there would seem to 

 be no possibility of varnish running in, the channel in the top of the 

 ring receiving the excess of balsam when pressed out by the cover, 

 and thus forming a barrier to the influx of the varnish used in ring- 

 ing. For flattening the rings he used two plates of brass, 2h in. 

 square by 1/8 in. thick. Place the rings, six or more at a time, 

 between the plates, and press in a lever stamp. This method of 

 mounting seems to him to have the following desirable features, viz. 

 no previous preparation and drying of cells, rapidity and neatness of 

 finish, and no running in of varnish. 



Styrax, Liquidambar, Smith's and van Heurck's Media — Dr. 

 H. van Heurck writes that styrax, when prepared by exposing the raw 

 product to the air and light, dissolving and filtering, is no longer of 

 a dark colour, and that its index is higher than 1"585, as given on 

 p. 475. The purified styrax of commerce is always darker and of 

 lower refractive index. Preparations become completely colourless 

 at the end of a few months, especially if brought into the light occa- 

 sionally, and the index rises a little. 



Liquidambar can be obtained of Lamman and Kemp, William 

 and Cedar Streets, New York. It must be heated to reduce its 

 brittleness, and dissolved by moans of the water-bath in a mixture of 



• Aiuer. Mull. Micr. Jdurii., v. (1884) pi). 84-5. 



