636 LECTURE XXVII. 



It is evident from this summary that the organs which are in constant 

 activity, as the heart, lungs, kidneys, and nervous system, suffer much less 

 loss of weight than the other organs. Voit also tested the influence of the 

 activity of an organ upon keeping its composition constant by feeding 

 doves with food which was deficient in lime, but contained a sufficient 

 amount of other materials. A post-mortem examination showed that 

 those bones which were in constant use had suffered less from the lack of 

 lime than relatively inactive bones, such as the breast-bone and the bill. 

 The last two bones had become perfectly porous. Evidently the composi- 

 tion of the bones which were used most was maintained at the expense of 

 the others. In this direction the observation of E. Pfliiger on dogs is 

 worth mentioning. He found, as has already been mentioned, 1 that when 

 the pancreas was extirpated the liver of these animals tended to gain 

 rather than lose in weight. Evidently the liver is an important place for 

 transformations, such as fat into sugar, etc. 2 



The loss in weight affects all the different substances contained in the 

 organs. The starving animal constantly loses water even when it is given 

 none to drink. Water is formed by the combustion of fat and albumin. 

 Mineral substances are likewise being eliminated constantly. The organs 

 maintain their functions as long as possible even in those cases where, as far 

 as we know, the organ is dispensable. Thus while the secretion of bile 

 diminishes, to be sure, during starvation, still, on the other hand, it con- 

 tinues to form for quite a length of time. Likewise the secretion of milk 

 continues for a time. On the other hand, the gastric secretion soon ceases, 

 as was shown by the examination of the contents of the stomach of the 

 fasting professional, Succi. 



A very important result of these starvation experiments is that the 

 animal organism constantly eliminates nitrogen under all conditions. To 

 be sure, the amount of decomposed albumin may become quite small, but 

 it never ceases altogether. Albumin assumes, as we have already shown 

 in discussing the Law of Isodynamics, 3 a peculiar position among our 

 organic foodstuffs. It cannot be entirely replaced by any other material. 

 It is possible to nourish a dog upon albumin alone, and even to fatten it 

 somewhat. This is never the case, however, when the total calorific 



1 Cf. Lecture V, p. 85. 



3 The observations concerning the relative loss of weight for the different parts of 

 the body are as a rule very inadequate and unsatisfactory. We have stated above the 

 generally accepted view concerning these relations, but we must say that the field has 

 not yet been well covered. There is no question but that a careful examination of the 

 losses of the different organs in their various constituents, naturally referred to average 

 values, will give us a new point of view concerning intermediate metabolism and of the 

 relations existing between the individual organs. The well-known experiment of 

 Miescher is the first step in this direction. 



8 Cf. Lecture XV, p. 336. 



