STORAGE TISSUES. 437 



These facts seem, very clearly, to show that proteids can- 

 not be built up quickly into tissues. Meat given to the 

 starving animal has its proteids, at first, used up mainly in 

 luxus consumption while a little is stored as tissue, though 

 at first not enough to counterbalance the daily tissue waste. 

 When a good deal more proteid is given than answers to 

 the nitrogen excretion during starvation, the animal builds 

 up as much into living tissues as it breaks down in the vital 

 Drocessesof these, the rest going in luxus consumption; it thus 

 neither gains nor loses. More proteid does not all appear in 

 the urine at once; some is used to build up new tissue, but 

 only slowly; then, after some days, the increased metabolism 

 of the increased flesh balances the excess of nitrogen in the 

 diet, and equilibrium is again attained. But, all through, it 

 seems clear that the tissue formation is slow and gradual; 

 and so it becomes additionally probable that the increased 

 urea excretion soon after a meal is not due to rapidly in- 

 creased tissue formation and degradation, but to a more 

 direct proteid oxidation. 



The Storage Tissues. Every healthy cell of the Body 

 contains at any moment some little excess of material laid 

 by in itself, above what is required for its immediate neces- 

 sities. The capacity of contracting, and the concomitant 

 evolution of carbon dioxide, exhibited by an excised muscle 

 in a vacuum, seem to show that even oxygen* of which 

 warm-blooded animals have but a small reserve, may be 

 stored up in the living tissues in such forms that they can 

 utilize it, even when the air-pump fails to extract any from 

 them. But in addition to the supplies for immediate spend- 

 ing, contained in all the cells, we find special food reserves 

 in the Body, on which any of the tissues can call at need. 

 These, especially the oxygen and proteid reserves, are found 

 largely in the blood. Special oxygen storage is, however, 

 rendered unnecessary by the fact that the Body can, 

 except under very unusual circumstances, get more from 

 the air at any time, so the quantity of this substance laid 

 by is only small; hence death from asphyxia follows very 

 rapidly when the air-passages are stopped, while, on account 

 of the reserves laid up, death from other forms of starva- 



