TAEALLEL CONDITIONS OF NUTRITION. 309 



tional activity is high and the nutrition defective, there re 

 sults not growth but decay. If in an animal, any organ ia 

 worked so hard that the channels which bring blood cannot 

 furnish enough for repair, the organ dwindles ; and if in the 

 body politic, some part has been stimulated into great pro 

 ductivity, and cannot afterwards get paid for all its produce, 

 certain of its members become bankrupt, and it decreases 

 in size. 



One more parallelism to be here noted, is, that the dif 

 ferent parts of the social organism, like the different parts 

 of an individual organism, compete for nutriment ; and 

 severally obtain more or less of it accoixling as they are 

 discharging more or less duty. If a man s brain be over 

 excited, it will abstract blood from his viscera and stop 

 digestion ; or digestion actively going on, will so affect tne 

 circulation through the brain as to cause drowsiness ; or 

 great muscular exertion will determine such a quantity of 

 blood to the limbs, as to arrest digestion or cerebral action, 

 as the case may be. So, likewise, in a society, it frequent 

 ly happens that great activity in some one direction, causes 

 partial arrests of activity elsewhere, by abstracting capital, 

 that is commodities : as instance the way in which the sud 

 den development of our railway-system hampered commer 

 cial operations ; or the way in which the raising of a large 

 military force temporarily stops the growth of leading in 

 dustries. 



The last few paragraphs introduce the next division of 

 our subject. Almost unawares we have come upon the 

 analogy which exists between the blood of a living body, 

 and the circulating mass of commodities in the body politic. 

 We have now to trace out this analogy from its simplest to 

 its most complex manifestations. 



In the lowest animals there exists no blood properly so 

 called. Through the small aggregation of cells which make 



