Chap, v.] NUTRITION. 621 



remark applies to the brain and spinal cord; in order that life 

 might be prolonged as much as possible, these important organs 

 were nourished by material drawn from less noble organs and 

 tissues. The blood suffered proportionally to the general body- 

 waste, becoming gradually less in bulk but retaining the same 

 specific gravity; of the total dry proteid constituents of the 

 body 17-3 p.c. was lost, which agrees very closely with the 

 17 - 6 p.c. dry material (almost wholly proteid) lost by the blood. 

 It is worthy of remark that the tissues in general became more 

 watery than in health. Similar observations on other animals 

 have led to similar results, the chief discordance being that in 

 some cases the bones have suffered considerable loss, in others 

 comparatively little. We might be inclined to infer from these 

 data the conclusions that metabolism is most active in the adi- 

 pose tissue, next in such metabolic tissues as the hepatic cells 

 and spleen-pulp, then in the muscles, and so on ; but we have 

 no warrant for these conclusions. Because the loss of cardiac 

 and nervous tissue was so small, we must not therefore infer 

 that their metabolism was feeble ; they may have undergone 

 rapid metabolism, and yet have been preserved from loss of sub- 

 stance by their drawing upon other tissues for their material. 

 The great loss of adipose tissue is obviously to be explained 

 by the fact that that tissue is essentially a storehouse of mate- 

 rial, and the similarly great though less loss in the spleen and 

 liver indicates, as indeed the facts recorded in the previous 

 chapter suggest, that these organs too serve in part as store- 

 houses. 



During this starvation period, the urine contained in the form 

 of urea (and that practically represents all the nitrogen of the 

 urine) 27*7 grammes of nitrogen. Now the amount of muscle 

 which was lost during the period contained about 15-2 of nitrogen. 

 Thus, more than half the nitrogen of the output during the 

 starvation period must have come ultimately from the metabolism 

 of muscular tissue. This fact we have already used in discuss- 

 ing the history of urea and shall have occasion to make further 

 use of it hereafter. The amount of urea excreted per diem has 

 been observed in some cases to fall very rapidly during the first 

 day or two of starvation, and then to diminish gradually, though 

 often shewing considerable irregularities. In other cases no 

 such large initial fall has been observed. It is most marked in 

 animals which have been well fed before the beginning of the 

 starvation, especially in those which have had a rich nitrogenous 

 diet ; and the discharge in these cases of an extra quantity of 

 urea in the first day or two is obviously connected with that 

 immediate effect of food on the excretion of urea to which we 

 have already (§ 385) referred and to which we shall have 

 to return in speaking of what is known as "luxus-consump- 

 tion." 



