312 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



the board. Pieces of black or white paper underneath will give the 

 backgrounds against which any object may be seen. For dissecting 

 in liquid a deep butter-plate answers well. If it is desired to have 

 transmitted light, the object may be dissected on the bottom of 

 an inverted tumbler which has a smooth concavity. Sloping blocks 

 may be placed at the sides for hand-rests. Still better illumination 

 may be had by fixing two such blocks, one on each side of the upright 

 rod, and placing between them a strip of mirror-glass inclined to an 

 angle of 30°-40°. In fact, with a little ingenuity and mechanical 

 skill, one may construct a stand for dissecting which will equal in 

 efficiency any of the simple Microscopes offered for sale." 



Hand -rests.* — Dr. E. H. Ward describes the hand-rests which he 

 has been accustomed to use, and which are made of mahogany strips 

 about 1 cm. thick, and 10 to 12 cm. wide, constructed as shown in 

 front view in fig. 55. 



Fig. 55. 



The rests are attached by hinges, and are held down firmly with 

 brass hooks, hinged strips supporting the rests at the desired height 

 and in an inclined position. Wooden buttons, held by large screws 

 fastened with brass nuts below, hold the base of the Microscope firmly 



Fig. 56. 



5 



m 



^ 



a 



7 x: 



^ 



5 



<^ 



c 



5 



in position. The hinges are all so arranged that the strips can be 

 folded together solidly, for portability, as shown in fig. 56, and held 

 in that position by the same hooks as when open. By a slight change 

 in size it is applicable to any dissecting Microscope. It should be 

 made of such size that the upper ends of the rests will be nearly 



* Bchrens' ' Microscope in Botany ' (Amer. ed. by Hervey and Ward), 8vo, 

 Boston, 1885, pp. 108-10 (2 figs.). 



