18 PHOTO-MICROGRAPHS. 
artificially ruled lines will long serve as models 
which less accomplished microscopists can scarcely 
hope to equal; for success in making photo- 
micrographs depends upon the skill of the opera- 
tor as a microscopist, and not simply as a photog- 
rapher. 
Indeed, the photographic part of the work may 
be delegated to another, and still the microscopist 
is properly credited with the result, as the merits 
of the picture, as a photo-nucrograph, depend upon 
his skill in preparing the object to be photo- 
graphed and projecting its image upon the screen ; 
while its merits as a photograph depend upon the 
technical skill of the operator who makes a perma- 
nent record of this image. This is done by the 
ordinary processes of photography, and it will be 
very desirable that the amateur who proposes to 
make photo-micrographs and, as must commonly 
be the case, to be his own photographer, should 
have a few lessons from a practical photographer. 
It is true that this part of the work is greatly 
simplified by the use of dry plates; but even with 
these, and with explicit printed directions with 
reference to their use, the beginner is pretty sure 
to expend a considerable amount of time and 
material, if he trusts to his unaided efforts, in ex- 
periments relating to time of exposure, develop- 
ment, etc. 
In the present volume, attention will be chiefly 
directed to that part of the art of making photo- 
micrographs which is the work of the microscopist, 
and the reader is referred to the nearest practical 
