PHYSIOLOGY. 



ulero-ges'tation, the scalp is covered with 

 a short and delicate hair; the nails are 

 formed ; the membrana pupillaris de- 

 stroyed ; the external car becomes firmer 

 and more elastic ; and the testes de- 

 scend. 



Besides the important changes in the 

 whole economy which follow parturition, 

 there are certain alterations in the exter- 

 r.ul habit of the body. The down which 

 covers the face at birth disappears; the 

 rugie of the skin are obliterated; the 

 anus becomes hidden between the but- 

 tocks, which are now gradually formed. 



The infant gradually brings into action 

 the faculties of the mind. It perceives 

 and attends to external objects, remem- 

 bers, desires, &c. It smiles in the second 

 month, and seems to dream at no great 

 length of time after birth. The organs 

 of sense become more complete in their 

 formation. The bones of the skull be- 

 come stronger, and the fontanells are di- 

 minished. Dentition commences about 

 the eighth month. The infant may then 

 be weaned, as his teeth enable him to 

 commence the use of more solid food. 

 About the end of the first year he learns 

 to stand on his feet, and to assume the 

 erect posture, that most distinguishing 

 attribute of the human body. 



"When it has now been removed from 

 the breast, and learned the use of the 

 lower limbs, its powers and independ- 

 ence increase daily, and receive a vast 

 accession from the developement of ano- 

 ther peculiar privilege of the human sub- 

 ject, the enjoyment of speech ; by which 

 the tongue, under the direction of the 

 mind, pronounces those ideas which are 

 now become familiar. 



At the seventh year the twenty milk 

 teeth begin to fall out, and are succeeded 

 in a gradual progress during the follow- 

 ing years by the thirty-two permanent 

 teeth. At this time the memory excels 

 all the other faculties of the mind ; where- 

 as about the fifteenth year the powers of 

 imagination begin to prevail. This is the 

 time of puberty, in which the human sub- 

 ject is gradually prepared, by various 

 "important changes, for the exercise of 

 the sexual functions. The breasts enlarge 

 in the female, the chin becomes covered 

 with hair in the male, and other similar 

 signs of puberty are noticed in both sex- 

 es. The menstrual discharge commences 

 in the softer sex ; and this important era 

 in the economy of the female is marked 

 !>y an increased expression in the eyes, 

 and redness of the iips, and more mani- 

 fest sensible qualities in the matter of 



perspiration. The seminal secretion be. 

 comes active in the male, attended with 

 an increase of the beard, and a deep- 

 ening of the voice consequent on a re- 

 markable developement of the larynx. 

 The internal and spontaneous calls of na- 

 ture now rouse the sexual instinct, for 

 the exertion of which both sexes are pre- 

 pared. 



No definite and precise period can be 

 assigned for the changes which constitute 

 puberty : it varies according to climate 

 and temperament. It is more early in 

 the female than in the male ; but in this 

 climate girls may be said to attain it at the 

 age of fourteen or fifteen, and men at se- 

 venteen or eighteen. Soon after these 

 periods the growth of the body is com- 

 pleted ; the stature of which varies much 

 in different races, not to mention its varie- 

 ties in individuals and families. The epi- 

 physes, which have hitherto been dis- 

 tinct from the body of the bone, are now 

 completely consolidated with it. 



Virility, Manhood, or JldultJige, begins 

 from the twenty -first to the twenty-fifth 

 year. If the increase of the body in height 

 have ceased at this time, it grows in other 

 dimensions. The organs become firm 

 and consistent ; their functions are per- 

 formed with vigour ; the intellectual and 

 moral faculties are perfected ; and the 

 dominion of the judgment succeeds that 

 of the imagination. This period, which 

 is called that of mature age, extends to 

 the fiftieth or fifty-fifth year in men, but 

 not much beyond the forty-fifth in wo- 

 men, in whom it begins earlier. During" 

 this long interval men enjoy all the pleni- 

 tude of their existence. 



Temperaments. As the characters of the 

 human species are now fixed with stabili- 

 ty, we may sketch the differences which 

 mark individuals. Health, in the expla- 

 nation of which all physiology is concern- 

 ed, consists in such a harmony and equi- 

 librium of the material fabric of the body, 

 and of its animating powers, as is neces- 

 sary for the performance of the various 

 functions. It requires, therefore, fluids 

 rightly prepared ; solids duly formed 

 from these ; the latter thoroughly animat- 

 ed by their vital powers ; and, lastly, a 

 sound mind in this healthy body. These 

 four principles are constantly acting and 

 re -acting in the human body. The fluids 

 act as stimuli on the solids ; which pos- 

 sess vital powers, enabling them to re- 

 ceive those stimuli, and to re-act. The 

 connection of the mind and body is not 

 discerned merely in the influence of the 

 will, in what physiologists cull voluntary 



