THE HUMAN BODY. 



CHAPTER I. 



THE GENERAL STRUCTURE AND COMPOSITION OF THE 

 HUMAN BODY. ' , 



Definitions. The living Human Body may be considered 

 from either of two aspects. Its structure may be especially 

 examined, and the forms, connections and mode of growth of 

 its parts be studied, as also the resemblances or differences in 

 such respects which appear when it is compared with other 

 animal bodies. Or the living Body may be more especially 

 studied as an organism presenting definite properties and 

 performing certain actions; and then its parts will be investi- 

 gated with a view to discovering what duty, if any, each ful- 

 fils. The former group of studies constitutes the science of 

 Anatomy, and in so far as it deals with the Human Body 

 alone, of Human Anatomy; while the latter, the science con- 

 cerned with the uses or in technical language the functions 

 of each part is known as Physiology. Closely connected 

 with physiology is the science of Hygiene, which is concerned 

 with the conditions which are favorable to the healthy action 

 of the various parts of the Body; while the activities and 

 structure of the diseased body form the subject-matters of 

 the sciences of Pathology and Pathological Anatomy. 



Tissues and Organs. Histology. Examined merely from 

 the outside our Bodies present a considerable complexity of 

 structure. We easily recognize distinct parts as head, neck, 

 trunk and limbs; and in these again smaller constituent 

 parts, as eyes, nose, ears, mouth; arm, forearm, hand; thigh, 

 leg and foot. We can, with such an external examination, 

 go even farther and recognize different materials as entering 

 into the formation of the larger parts. Skin, hair, nails and 

 teeth are obviously different substances; simple examination 



