IO PRACTICAL PHOTO-MICROGRAPHY. 
at one time ; and one of the processes on which stress 
shall be laid in this book is that of making lantern 
slides from photo-micrographic negatives. 
There is, unfortunately, little doubt that pre-concep¬ 
tions, “ personal equation,” and misinterpretation of 
microscopic images, tend to lead many of us astray in 
making drawings even with the optical appliances 
mentioned above ; and while by faulty manipulation of 
the microscope we may be led into false photographic 
renderings, still the personal equation and prejudica¬ 
tions are at least obviated by the use of photography.. 
And almost all teachers and investigators are now daily 
acknowledging the use of photo-micrography; there 
are now few schools or institutions of science that do 
not use photography more or less for purposes of edu¬ 
cation and demonstration, and the number is daily 
becoming smaller. Photo-micrography is not only the 
graphic science of to-day, but will in even greater 
measure be the graphic science of the future. 
Over and above all this there is the fact that those 
who have practised this science as a pastime, who have 
worked at it simply for its own sake, find this pursuit 
one of the most' engrossing interest and fascination ; 
and not without reason, for in our work we have much 
that is pleasing of optics, mechanics, chemistry, and 
art, with, as a result, a lasting, useful, often beautiful, 
record of some of Nature’s arcana. The man who takes 
up photo-micrography seriously, and aims at the best 
results in the most advanced and difficult branches, 
must give much time and earnest attention to it; but. 
