SOME ECONOMICS OF NATURE. 669 



mals, and receive oxygen (an action which, by the way, they also ex- 

 hibit by day), and emit carbonic acid. These facts do not affect the 

 main point at issue, which is the direct use by the plant of animal 

 waste, and a very pretty cycle of operations would thus appear to 

 have been established when botanical research showed the interactions 

 to which we have just alluded. 



Going a step further in the same direction, we may find that this 

 utilization of animal waste is by no means limited to the mere recep- 

 tion and decomposition of carbonic-acid gas by green plants. It may 

 be shown that the economical routine of Nature is illustrated in other 

 phases of the common life of the world. The general food of plants 

 is really animal waste. We fructify our fields and gardens with the 

 excretions of the animal world. The ammonia which plants demand 

 for food is supplied by the decay of living material, largely animal in 

 its nature ; and even the sordid fungi flourish- amid decay, and use up 

 in the system of natural economy many products for which it would 

 be hard or impossible to find any other use. What we, in ordinary 

 language, term " putrefaction " or " decay," is really a process of ex- 

 termination of the decomposing matter. No sooner does an organism 

 animal or plant part with vitality and become as the " senseless 

 clod," than thousands of minute organisms the "germs" of popular 

 science make it their habitation and their home. The process of 

 putrefaction, unsavory as it may be, is really Nature's way of picking 

 the once living body to pieces, of disposing of it in the most economical 

 way. So much of it is converted into gas, which, mingling with the 

 air, feeds the green plants as we have noted. So much of the dead 

 frame is slowly rendered into nothingness by the attack of the micro- 

 scopic plants which are the causes of decomposition. Nature says to 

 these lower organisms : " There is your food. In nourishing your- 

 selves, accomplish my further work of ridding the earth of yon dead 

 material." And so much, lastly, of the once living frame assuming 

 it to have been that of the higher animal as is of mineral nature, and 

 therefore resists mere decay, will in due time be dissolved away by 

 the rains and moisture, and be carried into the soil, to enter into new 

 and varied combinations in the shape of the minerals which go to feed 

 plants. Shakespeare must surely have possessed some inkling of such 

 a round of natural economics when we find him saying : 



11 Imperial Csesar, dead and turned to clay, 

 Might stop a hole to keep the wind away : 

 Oh, that that earth, which kept the world in awe, 

 Should patch a wall t'expel the winter's flaw ! " 



Continuing the study, we may see yet further glimpses of the 

 great system of general regulation which guards Nature from over- 

 drawing her accounts in connection with the arrangement of living 

 things. Not only in beings of high degree, but in animals of low 

 estate, do we meet with illustrations of the economy of power and the 



