174 



THE AMERICAN MONTHLY 



[September, 



of wood from the slide. The Plas- 

 modium will remain. The slide 

 should then be put very gently into 

 a mixture of equal parts of a sa- 

 turated aqueous solution of picric 

 acid and 95 per cent, alcohol; it 

 should be removed in 15 or 20 

 minutes, and placed, for about the 

 same length of time, in 95 per cent, 

 alcohol ; it may then be mounted in 

 Canada balsam in the usual 

 way, but without previous clear- 

 ing. 



The picric acid stiffens the proto- 

 plasm almost instantly, but does not 

 shrink it, the alcohol removes the 

 w^ater and allows of Canada balsam 

 mounting. 



The above method is especially 

 good for the yellow Plasmodium, as 

 the color is precisely that of the 

 picric acid solution. If white Plas- 

 modium is to be mounted it should 

 be soaked in 25 per cent, alcohol to 

 remove the yellow color of the 

 picric acid, before anhydrating it 

 with strong alcohol. 



Experiments have not been tried 

 with Plasmodium of purple and 

 other colors to determine successful 

 methods of preservation, but some 

 slight modification of the above is 

 confidently expected to succeed. 



SuMMAKY. A.— The Plasmodium 

 will crawl from rotten wood and 

 extend itself on a moistened glass 

 surface. 



B. — The extended Plasmodium 

 may be fixed in position by im- 

 mersing the slide on which it is 

 extended in a solution of picric 

 acid. 



C. — The slide may be placed in 

 95 per cent, alcohol to anhydrate the 

 Plasm^odium, after which it may be 

 mounted in Canada balsam. 



D. — The yellow Plasmodium re- 

 tains its natural color if treated in 

 this way. 



Ithaca, N. Y. 







The Microscopical Apparatus 



Exhibited at the Meeting 



of the A. A. A. S. 



Mr. Chas. Zentinayer was present 

 with a number of the beautiful 

 Zentmayer stands, but we did not 

 observe any noticeable improve- 

 ments in their form. Perhaps this 

 is because the makers do not think 

 they can be improved in design, and 

 we are inclined to the opinion that 

 they are quite right about it. Their 

 workmanship was fully equal to the 

 excellence for which Mr. Zentmayer 

 has been celebrated for so many 

 years. It is always a pleasure to be 

 able to give credit for good work, 

 and we do not hesitate to say that 

 the reputation which Mr. Zent- 

 mayer now enjoys as a maker of 

 stands, is justly deserved, and is the 

 result of many years of careful, 

 honest and conscientious workman- 

 ship. 



Messrs. J. "W. Queen & Co. were 

 represented by Mr. Edward Pen- 

 nock, who has charge of their 

 microscopical department. Their 

 exhibit was a creditable one, and 

 embraced many articles to attract 

 the attention of microscopists. 

 Among the novelties was a very 

 complete travelling microscope, 

 with, folding tripod base, double 

 mirrors, rack and pinion, fine 

 adjustment, society screw, and one 

 dividing objective. This instru- 

 ment stands about ten inches high, 

 and packs into a case about 

 6 X 3 X 2>^ inches. Also the 

 new model Crouch's "Histological" 

 monocular, which combines many 

 improvements, and Queen's new 

 sub-stage condenser was also shown. 



Mr. W . H. Walmsley, of Philadel- 

 phia, who always succeeds in having 

 the latest improvements in micros- 

 copes to exhibit at such meetings, 

 was provided with many articles of 

 interest. Among them probably 



