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 micros 

 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 

 wiU find that the prints differ just enough from the somewhat diar 

 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. 



