252 The Microscope. 



sue has been imbedded in celloidin, stained with logwood or 

 other stains, and finally mounted in balsam. 



Staining Nerves in Muscle.— For small muscles place por- 

 tions in a recent mixture of £ per cent, alkaline solution of gold 

 chloride, 1 grm.; 2 per cent, osmic acid, 1 grm.; water, 20 grm. 

 Let the tissue remain in this mixture until the nerve ramifica- 

 tions can be seen ; then in the following mixture : Glycerine, 

 40 grin.; water, 20 grm.; 25 per cent, hydrochloric acid solution, 

 1 grm.; for about a day. This prevents their becoming too dark. 

 Thicker muscles are placed in a 2 per cent, solution of acetic 

 acid for 12 hours, after which they are placed in a fresh mixture 

 of \ per cent, alkaline solution gold chloride, 1 grm.; 2 per cent, 

 osmic acid, 1 grm.; 2 per cent, acetic acid, 50 grm. In this they 

 remain for 2 or 3 hours, when they are transferred to the glycer- 

 ine mixture given above. The nerve-end-plate is stained by this 

 method. 



The Constituents of Clouds. — During a stay of three weeks 

 on the Brocken, Herr Assman examined a number of slides on 

 which drops of water had fallen. As the drops would fall on the 

 slide they were carefully measured. The smallest drops had a 

 diameter of .014 mm., when spread on the glass. The largest 

 were not above .018 mm. Lower down the mountain the drops 

 were about .02 mm. Still further down the average diameter 

 of the drops was about .035 mm. The smallest drops evaporated 

 slowly in from 10 to 15 seconds under the microscope without 

 leaving the slightest residue. At a subsequent examination 

 with a temperature of 10° C. he noticed that very small drops 

 of water fell on his slide ; not a single crystal of ice or snowflake 

 was visible among the drops. Nearly all evaporated quickly, 

 and some few froze to ice of the same size. 



EDITORIAL NOTES. 



We have for sale a fine Tolles 1-15 immersion lens, of su- 

 perior quality. It cost the owner $150, and he is ready to sell 

 it at 25 per cent, discount. Parties will please address us for 

 particulars. 



We are in receipt of one of Chapman's improved moulds 



