4 PREFACE 



The degree of magnification of the drawings and photographs 

 has been dehberately omitted. The statement to the effect that 

 a certain ilhistration is 600 or 1000 times the actnal size conveys 

 very Httle helpful information. The student will be constantly 

 using the microscope and will have little difficulty in appraising the 

 degree of magnification. A simple standard of measurement present 

 in many preparations is the diameter of the erythrocyte and by it 

 the size of other structures can be approximated when necessary. 



We have found it advisable to spend the first few weeks in the 

 laboratory in a first-hand study of the varieties of the different tissue 

 groups. The student is then given sections of organs and taught 

 to recognize the different tissues represented in them. Then the 

 tissue composition of organs is formally taken up. In a short time, 

 the student is quite independent of assistance from the instructor, 

 and this is as it should be. 



Each student should have for constant use during the semester 

 a well-selected set of slides loaned to him at the beginning of the 

 term and returnable at the end of the course. There should be 

 available a number of reference books and a complete set of lantern 

 slides of drawings and photomicrographs of preparations for use 

 during the laboratory sessions. Projection of microscopic prepara- 

 tions is a useful device for recitation purposes. Drawings are sug- 

 gested, not as artistic representations but as pictorial descriptions 

 of what the student actually sees. Unknown preparations are used 

 frequently to test the student's knowledge of tissues and organs 

 and his ability to apply it. At every step, the student is con- 

 fronted with new problems requiring observation and the exercise 

 of judgment in making decisions in identifying tissues or organs. 

 Such mental exercise is valuable training. 



Part of the time the student will spend in learning to make 

 preparations of the various organs studied, employing the more 

 general methods found by experience to be most satisfactory. 

 Mastery of technique is a worthwhile educational objective. There 

 should be available for constant reference one or more of the text- 

 books listed under the chapter dealing with technique, so that the 

 student may extend his knowledge of methods as time permits. 



The authors hope to have the privilege of being made aware of 

 the criticisms and suggestions which will undoubtedly arise in the 

 minds of those who use the book. 



New York City. (^t. G. S. 



J. I. K. 



