438 COMPARATIVE PHYSIOLOGY. 



Adipose tissues 97-0 per cent. 



Spleen 63'1 



Liver 56"6 " 



Muscles 30-3 " 



Blood 17-6 " . 



Brain and spinal cord O'O " 



It will be observed (a) that the loss of the fatty tissue was 

 greatest, nearly all disappearing; (6) that the grandular struct- 

 ures were next in order the greatest sufferers ; (c) that after 

 them come the skeletal muscles. 



Now, it has been already seen that these tissues all engage 

 in an active metabolism with the exception of adipose tissue. 



The small loss on the part of the heart, which is still less for 

 the nervous system, is especially noteworthy. The loss of adi- 

 pose tissue is so striking that we must regard it as an especially 

 valuble storehouse of energy, available as required. 



When we turn to the urine for information, it is found that 

 in the above case 37 grammes of nitrogen were excreted and 

 almost entirely, of course, in the form of urea ; and since the 

 loss of nitrogen from the muscles amounted to 15 grammes, it 

 will appear that more than one half of the nitrogenous excreta 

 is traceable to the metabolism of muscular tissue. It has been 

 customary to account for the urea in two ways : first, as derived 

 from the metabolism of the tissues as such, and continuously 

 throughout the whole starvation period ; and, secondly, from a 

 stored surplus of proteid which was assumed to be used up 

 rapidly during the early days of the fasting, and was the luonis 

 consumption of certain investigators. 



Comparative. — Experiment has shown that the length of 

 time during which different groups of animals can endure com- 

 plete withdrawal of food is very variable, and this applies to 

 individuals as well as species. That such differences hold for 

 the human subject is well illustrated by the history of the sur- 

 vivors of wrecks. Making great allowances for such devia- 

 tions from any such results as can be established by a limited 

 number of experiments, it may be stated that the human being 

 succumbs in from twenty-one to twenty-four days ; dogs in 

 good condition at the outset in from twenty-eight to thirty 

 days; small mammals and birds in nine days, and frogs in 

 nine months. Very much depends on whether water is allowed 

 or not — life lasting much longer in the former case. The very 

 young and the. very old yield sooner than persons of middle 



