ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 833 



osmic acid, and colour it with CoUin-black acidulated by chromic acid to 

 which glycerin has been added. 



New Method for making Microscopical Preparations from Test- 

 tube Cultivations.* — Dr. E. Fischl recommends the following procedure 

 for obtaining microscopical preparations from test-tube cultivations : — 

 By means of a cork-borer the central track is removed from the gelatin. 

 This gelatin cylinder containing the micro-organisms is then placed for 

 24-48 hours in 96 per cent, alcohol or in a mixture of equal parts of 

 ether and alcohol, and then sectioned on a microtome between cork 

 layers. The sections are then stained by Gram's method, the micro- 

 organisms alone retaining the stain. The author has applied the 

 foregoing to the examination of ferment-fungi with excellent results. 



Chitin Solvents.f — Mr. T. H. Morgan reports the results of experi- 

 ments which he has made with chitin solvents. He followed a prescrip- 

 tion recommended by Dr. Loob,J namely, Labaraque solution (potassium 

 hypochlorite) and Javelle solution (the corresponding sodium com- 

 pound). Mr. Morgan used the solutions successfully in two forms, 

 strong as in the commercial fluid, weak when diluted from five to six 

 times with water. In most cases the strong solution acts too rapidly 

 and powerfully. The preparations after removal of the chitin were 

 hardened in picro-sulphuric acid, corrosive sublimate, or different 

 strengths of alcohol. The method was also used for specimens already 

 hardened and preserved. The experiments seem to show that something 

 else in the compound besides free chlorine is brought into play. 



Preparing Slides to show Brownian Movement.§ — Prof. H. M. 



Whelpley says that permanent mounts to illustrate the phenomenon of 

 pedesis are not difficult to make, " provided, however, that the motion 

 does not cease after a few days, as claimed by some authorities." He 

 has " no reason for doubting the statement of one writer, who says he 

 has a mount six years old that shows the movement nicely and as well 

 as it ever did." Place a well-cleaned slide on the turntable and run 

 a ring of cement on it about • 5 mm. hrgh. In warm weather, or in a 

 warm room during winter, the cement will become sufficiently dry in 

 a half hour to permit of finishing the mount. This is accomplished by 

 placing in the cell a large drop of a liquid made by mixing carmine or 

 other powders || with 100 times its volume of water, and placing in posi- 

 tion a well-cleaned cover-glass. When the cover is pressed down, the 

 superfluous liquid will be pressed out and the fresh cement will hold 

 the cover firmly to the cell. The pressure reduces the depth of the cell 

 to about 0-25 mm. The slides should be washed to remove any par- 

 ticles of the powder that may have run out with the liquid and been 

 deposited on the cover-glass. When dried it is ready for use, and such 

 a mount, at least as far as the mechanical part is concerned, will last a 

 lifetime. Either white zinc cement or Brunswick black can be used. 



* Fortschr. d. Med., v. (1887) p. 653. 



t Stud. Biol. Lab. Johns-Hopkins Univ., iv. (1888) pp. 217-9. 

 X See this Journal, 1885, p. 896. 

 § Amer. Mou. Micr. Journ., ix (1888) pp. 125-7. 



II Vermilion, cobalt, wood charcoal, indigo, camboge, pumice stone, carbonate of 

 lead, glass. 



