THEIR MODE OF ACTION. 369 



body which are not essential to life, without the 

 other, parts taking a share in the decomposition ; it 

 is termed malignant when they affect essential 

 organs. 



It cannot be supposed that the different changes 

 in the blood, by which its constituents are con- 

 verted into fat, muscular fibre, substance of the 

 brain and nerves, bones, hair, &c., and the trans- 

 formation of food into blood, can take place without 

 the simultaneous formation of new compounds, 

 which require to be removed from the body by the 

 organs of excretion. 



In an adult these excretions do not vary much 

 either in their nature or quantity. The food taken 

 is not employed in increasing the size of the body, 

 but merely for the purpose of replacing any sub- 

 stances which may be consumed by the various 

 actions in the organism ; every motion, every mani- 

 festation of organic properties, and every organic 

 action being attended by a change in the material 

 of the body, and by the assumption of a new form 

 by its constituents.* 



But in a child this normal condition of suste- 

 nance is accompanied by an abnormal condition of 

 growth and increase in the size of the body, and of 



* The experiments of Barruel upon the different odours emitted 

 from blood on the addition of sulphuric acid, prove that peculiar sub- 

 stances are contained in the blood of different individuals; the blood 

 of a man of a fair complexion and that of a man of dark complexion 

 were found to yield different odours ; the blood of animals also differed 

 in this respect very perceptibly from that of man. 



B B 



