APPENDIX A. 249 
term magnifying power by examining the same simple object as seen 
: 
with several powers. For instance, a letter of ordinary print (e.g., 
the finest used in this book), may be examined with the naked eye 
and with the magnifying glass. Then sketches on cardboard may 
be handed round to show the size of the object, drawn with the 
camera lucida as seen under the 2-inch objective, with others drawn 
to scale, to show the effect of all the other magnifying combinations 
which the microscopes belonging to the school afford. 
For further suggestions in regard to the manipulation and use of 
the microscope the teacher is referred to any of the standard works 
on the subject. The little book of Charles H. Clark, cited in the 
bibliography (Appendix D), is compact and usable. 
An important adjunct to the microscopical work (or, if need be, a 
partial substitute for it) consists in the use of photomicrographs of 
the most important tissues. The mounted silver-prints, or unmounted 
blue-prints, may be numbered and given out to the division for study 
at the desk after the structure in question has been studied with the micro- 
scope. Ample time should be given for careful examination of the 
pictures thus given out, and then the members of the division may 
be questioned individually on the photographs, or a written exercise 
may be set, in which all shall write as fully as possible about a 
designated number of the photomicrographs examined. The teacher 
will find that the prints differ just enough from the somewhat dia- 
grammatic or idealized cuts usually given in books to afford an 
admirable opportunity for the pupil to exercise his powers of observa- 
tion and discrimination in making out the exact nature of the several 
tissue elements to be found in each photograph. 
