1886.] 



MICROSCOPICAL JOURNAL. 



65 



convey a small amount of pollen from 

 the bottle to the drop of turpentine on 

 the slip. Cohering masses of pollen 

 should be separated with the needle 

 and spread as evenly as possible over 

 one-eighth of an inch of space on the 

 slip. A small drop of balsam, just 

 sufficient for the purpose, is then 

 dropped on the pollen. 



The next specimen of pollen is 

 similarly arranged over another spot, 

 and a small drop of balsam applied 

 as before. When the several pollens 

 are in place the slide should be set 

 aside and covered with dust for 

 twenty-four or forty-eight hours, or 

 until the balsam has become some- 

 what hardened and the pollens fixed 

 in their respective places. A drop 

 of fresh balsam may then be placed 

 in the centre between the groups and 

 a cover applied with very gentle pres- 

 sure, and all allowed to harden as 

 usual. If the first balsam drops are 

 not sufiiciently hard when the cover- 

 glass is adjusted the fresh balsam will 

 liquify all too rapidly, and the pol- 

 lens will run together or creep out 

 with the surplus balsam. 



Too strong a pressure will also 

 cause the pollens to mix by producing 

 currents in the balsam as the cover 

 settles into place. 



The names of the flowers from 

 which the pollens were gathered 

 should be written on the label in 

 small characters and occupy the same 

 relative positions as the specimens 

 do under the cover. This will enable 

 one to find a given specimen or name 

 quickly. 



This method may be employed for 

 foraminifera seeds, diatoms, scales, 

 or any other small objects which 

 might be placed together for tlie pur- 

 pose of comparison. 



vS. G. Shanks. 



The Mounting' of Diatoms.* 



BY E. DEBES. 



Regarding mounting media, I wish 

 to remind the reader that, notwith- 



* Translated and condensed from Nedwigia by F. 

 Dienelt. 



standing the high refractive index of 

 monobromide of naphthaline, Thou- 

 let's solution or phosphorus, on ac- 

 count of the many difficulties in ma- 

 nipulation and the great uncertainty 

 as to durability, the use of these me- 

 dia cannot be recommended. I have 

 obtained very good results from st}- 

 rax and liquidambar, refractive in- 

 dex about 1.63, and after consider- 

 able experience am fully convinced 

 that both media possess very desira- 

 ble qualities, and are as easily manip- 

 ulated as Canada balsam, but never 

 become as brittle as the latter. The 

 brown color, especially of styrax, 

 does not much exceed that of old 

 Canada balsam and is said to disap- 

 pear entirely on bleaching in direct 

 sunlight. 



Styrax or storax, Liquidaniba}- 

 oricjitalis Miller, is a native tree of 

 Asia Minor and Syria. Gum styrax, 

 the product, contains cinnamic acid 

 and styracin, both soluble in petro- 

 leum ether or petroleum benzine. 

 By adding either of these to the gum 

 in a shallow vessel over a hot-water 

 bath, and stirring well with a glass 

 rod, both components are easily got 

 rid of. The styrax has to be thor- 

 oughly dehj'drated after pouring ofl' 

 the solution. A bottle contained 

 sixty grams, price two francs and a 

 half, but was found not to be per- 

 fectly free from styracin, and had to 

 imdergo a short process. 



Liqziidambar styracljliia L. is 

 a native tree of the United States, 

 similar to styrax in all respects, and 

 has to be treated the same. Balsam 

 of tolu, recommended by Mr. C. H. 

 Kain, I found in my experiments in 

 no way superior to Canada balsam ; 

 its refractive index is slightly above 

 it, but can never reach, far less ex- 

 ceed, that of styrax. In mounting 

 the more roliust and all convex and 

 strongly cur^■ed forms, Canada bal- 

 sam, owing to its lighter color, is 

 preferable. Before using, Canada 

 balsam ought to be heated in a shal- 

 low vessel over a hot-water bath, 

 stirred well with a glass rod, up to 



