1880.] 



MICROSCOPICAL JOURNAX,. 



199 



construction, yet simpler. Mr. White uses 

 hydraulic pressure, with a fourth pipe 

 through the cork of the receiver to pre- 

 vent overflow and destruction of the in- 

 jecting fluid. But may not the pressure 

 of the water be so great, that while one's 

 attention is occupied with the process of 

 injecting, the water will overflow ? In Dr. 

 Froehling's apparatus, air is used instead 

 of water and it is applied by means of a 

 Davidson syringe. This is somewhat more 

 tedious than the water process, but there 

 is no danger of causing any overflow. The 

 receiver is a " passive recipient " in the 

 form of a demijohn, and the canulae are of 

 glass (home-made, — as many of our in- 

 struments should be). 



Why is it that works on microscopy do 

 not describe any but the most costly ap- 

 paratus ? In my experience, those most 

 interested in this branch of science are 

 the least able to bear the heavy expendi- 

 tures of money which the books require. 

 Then let us try to invent cheap instead of 

 costly instruments. 



Chas. H. Cockey, M. D. 



Baltimore, Sept. 1880. 



GLASS FOR SLIDES. 



To THE Editor : — To the inquirers 

 in the JOURNAL about glass for slides, my 

 experience may be of use. 



Between the years 1877 and 1878, I 

 made many inquiries for glass for this 

 use, at all the principal glass importing 

 houses in Boston, New York and Phila- 

 delphia. I wanted a reasonably good 

 article, thin, clear, flat, smooth, and at the 

 lowest price. At last I settled on a glass 

 bought of Adolf Forster, 206 Church 

 Street, Philadelphia (in 1877 and 1878), 

 and sold by him as " Thin %" white plate 

 glass." This was in sheets 10^ x 17 

 inches, thirty sheets in a box. This he 

 had (1877-78) sold at 65 cents per single 

 sheet, or 60 cents per sheet by the box. 

 A sheet cuts into 56 slides, there is a 

 little waste. I cut my slides myself, taking 

 off the rough, sharp edges on a stone. 



This glass is a polished plate glass, 

 with good surface, and somewhat bluish- 

 green in color. From 650 slides cut from 

 glass bought in 1877, I selected 50 of the 

 thickest and 50 of the thinnest. The 

 thickest 50 averaged 1.43'""'-' in thick- 

 ness, the thinnest 50 averaged 1.18'"™- A 

 lot cut in 1878 averaged l.'^S'"™- thick. I 

 have paid as high as 40 and even 60 cents 

 per dozen for slides not so good as these 

 are. Yours truly, 



Wm. H. Brewer. 



New Haven, Conn. 



[Prof. Brewer has favored us with some 

 of the slides above mentioned, for exami- 

 nation. They are very thin and clear, and 

 are the best home-made slips we have 

 seen. — Ed.] 



BALSAM BOTTLE. 



To the Editor: — In your July num- 

 ber at page 139, is a description of a new 

 mounting bottle for balsam, damar, etc. 

 The device is simple and effective, but in 

 my hands the mouth of the bottle is sure, 

 sooner or later, to receive a touch of the 

 balsam, and then the cork is apt to stick 

 and twist off, and bits of cork to drop into 

 the balsam. I have had a wooden plug 

 turned for my balsam bottle, through the 

 centre of which a hole is bored. Through 

 this is inserted an ordinary rubber-topped 

 dropping-tube. So far this arrangement 

 has worked better with me than a cork. 



W. 



DRY MOUNTS OF POLLEN. 



To THE Editor: — In making a dry 

 mount of the pollen of some kinds of flow- 

 ers, as for instance, the red salvia, a dewy 

 appearance may be noticed on the cover- 

 glass between the pollen grains. In the 

 case of the red salvia, this " dew " has not 

 been affected by two hours heating in the 

 " dryer " of a kitchen stove, so I take it 

 that it is not water, but some viscid me- 

 dium from the anther. The damp appear- 

 ance does not interfere with examination 

 of the pollen grains, but it is rather un- 

 sightly, and I would be obliged if some- 

 body would suggest a means to get rid of it. 



A. L. W. 



OBJECTIVES. 

 To THE Editor: — Mr. L. R. Sexton, 

 of Rochester, has been kind enough to 

 send me, from time to time, some of Mr. 

 Gundlach's objectives, among others the 

 1-10-inch of class " D." It having been 

 claimed that this objective would resolve 

 A. pellncida by simple illumination with 

 mirror and lamp, when I received the ob- 

 jective, I tried it on a balsam-mounted 

 Moller's test plate, and thought that a glass 

 at the price it is sold, would do well, if it 

 would resolve the longitudinal lines on 

 number 16, but to my surprise it resolved 

 these, as well as numbers 17, 18 and 19. — 

 I then tried number 20, not expecting to 

 succeed, however, but to my great surprise 

 and delight, did succeed to plainly resolve 

 the lines on A. pellucida, and I did not 

 use anything except mirror and lamp for 

 illumination. 



