104 PHOTO-MICROGRAPHS. 
cal form and transparent contents— protoplasm 
—of a cell of this kind, and is consequently 
more satisfactory, as interpreting nature, than 
the deeply stained cell in Fig. 1. Those, how- 
ever, who are accustomed to seeing natural 
objects represented by wood-cuts and with print- 
er’s ink, will perhaps prefer the sharper contrast 
obtained by the use of staining agents. 
The scales of the Lepidoptera — butterflies and 
moths —are suitable objects for photography, and 
some of them are especially imteresting to micro- 
scopists for the reason that they are used as tests 
of the performance of objectives. They may be 
mounted dry, and extemporaneous preparations 
are quickly made by applying the wing or body 
of a lepidopterous insect to the surface of a clean 
glass slide. 
BuLoop-CoRPUSCLES. 
The blood-corpuscles of man and the lower 
animals are among the objects most suitable for 
photography. Comparatively high powers will be 
required ; and, for purposes of comparison as to 
dimensions, it is well to adopt a standard of ampli- 
fication, say one thousand diameters. 
The writer’s best results have been obtained 
with the one-twelfth and one-eighteenth inch ho- 
mogeneous immersion objectives of Zeiss. 
The corpuscles are spread upon a thin glass 
cover in as uniform a layer as possible, and are 
allowed to dry im situ. They do not require 
staining, and are mounted, dry, over a circle of 
cement. 
