230 THE AMEEICAN MONTHLY . [October, 



ished and preserved for future reference. Balsam of fir makes starches 

 too transparent. Glycerin is good, but it is almost impossible to find 

 a cement that would hold it on account of its solvent properties. Car- 

 bolic acid and water in time dry out. Cosmoline has been recom- 

 mended, but it is too greasy and it has the same fault as glycerin ; it is 

 almost impossible to find a cement that will hold it. 



A short time ago Mr. Charles Bullock spoke to me of a new medium 

 he had been using to monnt vegetable tissues ; it struck me as being 

 the very article for mounting starches in. I prepared some and found 

 it to answer the purpose admii-ably ; it is as follows : ^ 



Selected gum ai^abic . . . . . . 5 ij 



Glycerin ..... . . 



Distilled water, of each . . . . , . f § iss 



Thymol . . ..'.... gr. i 



These are all placed in a wide-mouth bottle, which is corked care- 

 fully to exclude dust and placed in a warm situation. It takes several 

 days to effect a perfect solution, the mixture being stirred up occasion- 

 ally. When all is dissolved strain through linen and set aside the 

 liquid about a week longer to get rid of air-bubbles and to allow any 

 small particles that may have passed through the strainer to settle to 

 the bottom, or it can be filtered through absorbent cotton by using a 

 funnel for hot filtration, which consists of a double tin case holding 

 water kept at the required temperature by a spirit lamp placed under 

 the projecting arm. A glass funnel fits inside of the hot-water bath, a 

 plug of absorbent cotton is placed in the funnel, and the solution is 

 passed thi^ough it. After filtration it is best to preserve in compres- 

 sible tubes. 



To mount starches or pollens a clean slide is breathed on and then 

 dusted over with the starch or pollen to be mounted ; the surplus is 

 removed by gently tapping the slide against any hard substance — a 

 table, for instance. Enough of the staixh will adhere to the slide and 

 will be nicely distributed over the field. A drop of the mounting me- 

 dium is now placed on the slide carefully and the cover placed over it. 

 If there are any air-bubbles in the mounting medium when placed on 

 the slide they should be carefully picked out with a mounting needle. 

 If the medium is kept in a compressible tube there is not much danger 

 of air-bubbles on squeezing out a drop; or if there are any, they will 

 be on the surface, and can be readily removed with a mounting needle. 

 The slide can be finished immediately by i^unning a ring of any kind 

 of cement around the edges of the cover-glass, and the mount is per- 

 manent. 



The medium can be colored blue by adding a small quantity of ani- 

 line blue, although it is not necessary, as the structure of the starches can 

 be plainly seen. They should be examined by central and oblique il- 

 lumination and with the polariscope to give the student interested in 

 this subject an idea of the beauty of starches and pollens. —yl?/?. your. 

 Pharm. 



Slides Received. — We desire to return thanks to the donor for 

 the following interesting histological slide : 



Blood of snapping-turtle mounted in osmic acid glycerine, by Wm. 

 N. Beggs, M. D., St. Louis, Mo. 



