118 PHOTO-MICROGRAPHS. 
may be done in this direction. But there are 
obstacles to be encountered which make it neces- 
sary that one who hopes to equal these produc- 
tions of a skilled microscopist shall at least possess 
a tithe of his patience and persistence in surmount- 
ing technical difficulties. The writer has given 
but little time to this kind of work, having de- 
voted his attention mostly to photographing uni- 
cellular organisms, and especially to the Bacteria. 
Manuals of histology and of microscopical tech- 
nology must be consulted by one who proposes to 
prepare his own specimens for photography, as is 
strongly recommended. 
The following named works will give all neces- 
sary information, so far as the technique has been 
perfected ; but the student should not blindly fol- 
low any teacher. Keeping in mind the general 
requirements due to the restrictions imposed by 
the laws of optics and the optical appliances used, 
and making himself familiar with the structural 
details which it should be his aim to show plainly 
in his photo-micrographs, the operator should avail 
himself of all the information to be derived from 
text-books, and at the same time make every effort 
to improve the technique for this special purpose. 
A little work by Professor Schafer, of Univer- 
sity College, London (“ Histology and the Micro- 
scope’), will be found especially useful by begin- 
ners. More advanced students should have in 
their libraries the following works: “The M1i- 
croscope and Microscopical Technology,” Frey 
(William Wood & Co., New York); “A Manual 
