

TO THE TEACHER 



THE human body is made of cells and its life consists 

 in the activities of the cells. Physiology is the study of 

 the cells and tissues in their related activities. Yet the 

 usual school physiology neglects the functions of the 

 cells and tissues and studies organs almost as isolated 

 things, rather than as component parts of the bodily 

 structure. The well organized science of physiology is 

 thus slighted and the result is an unnecessary waste of 

 time. The experience of the author with young students 

 has convinced him that elementary facts in the science are 

 not so difficult of comprehension when given in their real 

 relations as when given as isolated facts. 



But due regard solely for logical order would require that 

 the pupil be inducted at once into the study of protoplasm 

 and cells, which are to him mysterious subjects. The 

 interest naturally excited by beginning a new study would 

 be killed before he reached things that he knows some- 

 thing about. The science of teaching requires that we 

 begin with things well known to the pupils and proceed 

 through the known to the unknown. Evidently no subject 

 is so well adapted for the starting point as the skin. The 

 surface of the body is familiar ; personal appearance is a 

 subject of interest to young people ; for these reasons the 

 skin is a suitable subject for introducing the stucty. Cell- 

 life being an unknown subject, it is treated at first in the 

 simplest and most elementary manner, but constant return 

 to it is made in the discussions of each organ and func- 

 tion. As the nerves are intimately related to every 

 organ, some authors attempt an exhaustive treatment of 



