350 LECTURE XVI. 



is true of all the glands taking part in the digestive processes, beginning 

 with those of the stomach and the mucous membrane of the alimentary 

 canal, on to the large digestive glands of the pancreas and liver. In all 

 such cases the organism suffers a constant loss of material. Again, the 

 organism constantly requires the presence of salts, and water to flush out 

 the waste material through the kidneys. Further, we have to consider 

 the specific tasks of the single cells and cell-groups by means of which 

 definite products are developed which play an important part in the metab- 

 olism of the organs, whether it be a ferment, or some other product such 

 as adrenalin, which is formed in the suprarenal gland. 



Furthermore, the fact that there is evidently a lively breaking down 

 and building up even in tissues which we would scarcely expect to par- 

 ticipate in active metabolism, is shown to us by a histologic study of the 

 bones, which show evidence of a continual exchange of their building 

 material. From the field of pathology, we find that the building up of 

 the nerves and their restitution under some conditions may assume con- 

 siderable dimensions. This is shown, for example, in the case of hyper- 

 trophic activity, which appears as soon as there is an additional require- 

 ment placed upon a certain organ, whether because of the fact that it 

 must act as a substitute for another, or whether because its work becomes 

 increased in some other abnormal way, as, for example, in the case of the 

 heart in certain kinds of heart trouble. On the other hand, in conva- 

 lescence after certain fevers, particularly typhoid, we find a sudden reju- 

 venation of the sunken cell-energy. Each cell takes up the building 

 material from the circulating nourishment, and this is particularly true of 

 albumin, which in a certain sense determines the functional activity of 

 the cell. In a short time the organism is renewed. The loss of albumin 

 which the body has experienced during the disease is quickly compen- 

 sated. The old equilibrium in the economy of the cells is again estab- 

 lished. Again, a sudden increased production of cell-material takes place 

 after some local irritation. Thus we find that the organism concentrates 

 a great number of leucocytes at an infected point, and finally perhaps 

 large masses of pus are formed, all at the cost of the nourishment and the 

 material composing the organs. On the other hand, sometimes we find 

 the organism throwing off considerable quantities of exudate, as, for 

 example, in pneumonia, which again uses up large amounts of material. 

 On the other hand, if we consider the continual variations in the number 

 of red and white corpuscles, and the variations in the lymphocytes, we 

 obtain the impression that the cell-material of the fully developed organism 

 is never at rest. We know practically nothing concerning the quantitative 

 relations involved in all such changes. We do not know whether the 

 material in the old cells is used to some extent in building up new ones, 

 or whether the new cells are entirely formed from new material. We do 



