408.  The Question of Apparatus.  The author well understands from personal experience the many practical difficulties in the way of providing a suitable amount of apparatus for classroom use.  If there are ample funds for this purpose, there need be no excuse or delay in providing all that is necessary from dealers in apparatus in the larger towns, from the drug store, markets, and elsewhere.  In schools where both the funds and the time for such purposes are limited, the zeal and ingenuity of teachers and students are often put to a severe test.  Fortunately a very little money and a great deal of ingenuity and patience will do apparent wonders towards providing a working supply of apparatus.

It will be noticed that many of the experiments in the preceding chapters of this book can be performed with very simple, and often a crude and home-made sort of apparatus.  This plan has been rigidly followed by the author, first, because he fully realizes the limitations and restrictions of the subject; and secondly, because he wishes to emphasize the fact that expensive and complicated apparatus is by no means necessary to illustrate the great principles of anatomy and physiology.

409.  Use of the Microscope.  To do thorough and satisfactory work in physiology in our higher schools a compound microscope is almost indispensable.  Inasmuch as many of our best secondary schools are equipped with one or more microscopes for use in other studies, notably botany, it is much less difficult than it was a few years ago to obtain this important help for the classes in physiology.

[Illustration:  Fig. 170.—­A Compound Microscope]

For elementary class work a moderate-priced, but well-made and strong, instrument should be provided.  If the school does not own a microscope, the loan of an instrument should be obtained for at least a few weeks from some person in the neighborhood.

The appearance of the various structures and tissues of the human body as revealed by the microscope possesses a curious fascination for every observer, especially for young people.  No one ever forgets the first look at a drop of blood, or the circulation of blood in a frog’s foot as shown by the microscope.

[NOTE.  For detailed suggestions in regard to the manipulation and use of the microscope the student is referred to any of the standard works on the subject.  The catalogues of scientific-instrument makers of our larger cities generally furnish a list of the requisite materials or handbooks which describe the use of the various microscopes of standard make.

The author is indebted to Bergen’s Elements of Botany for the following information concerning the different firms which deal in microscopes.  “Several of the German makers furnish excellent instruments for use in such a course as that here outlined.  The author is most familar with the Leitz microscopes, which are furnished by Wm.