152 SWINE 



that the $25 per month that was set aside at the beginning 

 with which to increase his bank account will gradually be 

 cut down, and before very long there will come a time 

 at which he will have established a money equilibrium, 

 or, in other words, the total receipts from his salary will 

 just balance his total expenditures, which will result in 

 zero as far as increasing his bank account is concerned. 

 In order now to further increase his bank account, his 

 salary must be raised, say to $75 per month. This for the 

 time being will again allow him to set aside $25 per 

 month, but as time again progresses his expenses will 

 naturally increase so that before many years have elapsed 

 he will again have established an equilibrium between 

 his income and expenditures. In order to allow a further 

 increase in said bank account the salary must again be 

 increased to, say $100 per month. The process will here 

 be repeated, allowing an increase in the bank account at 

 first and again establishing an equilibrium later on. This 

 illustrates the tendency in the animal body toward nitro- 

 gen equilibrium, namely, to excrete as much nitrogen as 

 is taken in in its food. 



The establishment of the factor of waste, or the higher 

 rate of living in the case of the young man, is not an abso- 

 lute necessity, but the natural result of prevailing condi- 

 tions. Thus also a pig, apparently, does not necessarily 

 have to establish the factor of waste, but usually does 

 under prevailing conditions of high feeding because either 

 too much is fed, or the amount fed to a bunch is not 

 equally distributed, resulting in an excess for those eating 

 the most ; or, the environment may be changed so that 

 the pig cannot use a constant quantity and is fed the same 

 as usual. 



If the pig requires .1 pound of protein per day per 



