IV PREFACE. 



can be prepared at home to good advantage are Nos. 4, 6, 

 7 (last half), 9, 10, 13, 14, 15 (first half), 16, 17, 24, 29, 

 31, 32, 33, 36, 41, 42, 43, 45, 46, and the larger part of 

 48 and 49. Whenever the abbreviation (Dem.) is found 

 in any part of an experiment, a demonstration will be 

 given by the instructor. 



The most satisfactory method of recording laboratory 

 work I find to be this. The observations and conclusions 

 are stated briefly by the pupil in his note-book as the work 

 is done. Some little time is taken for discussion at the 

 close of the period, when the facts are clearest in mind, 

 special care being taken to see that correct inferences have 

 been drawn. That the work of the day may be more 

 firmly fixed in the pupil's mind, he is required to write on 

 paper of a certain kind and size, and to present at the next 

 lesson a carefully prepared statement of (1) the steps in the 

 experiment, (2) the results observed, (3) the conclusions 

 which were drawn from the experiment. These papers, 

 together with the drawings and other work prepared in 

 class, are arranged in a cover belonging to each pupil, and 

 constitute his laboratory book. 



The descriptive terms dorsal and ventral, anterior and 

 posterior, median and lateral, employed in comparative 

 anatomy, are used in the following directions, since they 

 seem preferable to the more indefinite terms front and 

 back, upper and lower, middle and side, commonly used 

 in books on human physiology. I have adopted through- 

 out the food study the term nutrients (for food-materials, 

 foodstuffs), and nitrogenous substances (for proteids, albu- 

 minoids, gelatinoids, etc.); these terms are used in the 

 publications of the II. S. Department of Agriculture. 



We have found the study of the material at the American 

 Museum of Natural History (especially the skeletons and 



