6 



THE 3IICR0SC0PE. 



Jan. 



the back of the knife towards the strop and without pres- 

 sure of the liand, see Fig. No. 2. If the knife will now 

 cut a hair freely along the entire edge it has attained 

 the requisite keenness of a microtome knife, and after 

 it has again been wiped off with a soft chamois skin it is 



ready for cutting. It is to be suggested that the strop 

 is slightly covered with oxide of iron, and rest on a 

 flat and firm support. We recommend for this purpose 

 a bow strop. Before each cutting of the preparations 

 the knife should be passed over the strop. 



Photographing Certain Natural Objects Without a Camera. 



By prof. W. a. KBLLERMAN, Ph. U. 

 COLUMBUS, OHIO. 



The objects referred to are those which are transpar- 

 ent or translucent, more particularly ordinary foliage 

 leaves, and other botanical specimens, wings of certain 

 insects, fins of fishes, etc. The process consists in using 

 the object itself as the negative and jjrinting from it in 

 a photographer's printing frame, in the usual manner. 



