ACTIVIXr OF ORGANIC LIFE. 89 



alive the race, as plants have all their energies con- 

 centrated to produce seed. The domesticated cov? 

 lives to continue her race and to nourish human 

 beings, so that every support must be given to what- 

 soever will tend to develop her whole organism into 

 the form and activity that conduces to this double 

 service. 



Given the proper organs, perfect in form and 

 adaptation to ends, the cow may be a poor thing, if 

 there is sluggish movement throughout her whole 

 organization. To produce a quart of milii an hour, 

 or half or quarter this quantity, signifies activity of 

 organs. This will appear when we consider the waste 

 and renewal of parts that is a phenomenon of life. 



Carpenter, in his Physiology, says the whole struc- 

 ture originates in a single cell ; that this cell gives 

 rise to others analogous to itself, and these again to 

 many future generations ; and that all the varied tis- 

 sues of the animal are developed from cells. As fast 

 as one cell is destroyed another is generated. The 

 death of one is followed instantly by the birth of its 

 successor. This continual jDrocess of cellular death 

 and birth, the income and outgo of cells, that follow 

 each other like the waves of the sea, each different 

 yet each the same, is metamorphosis of tissue. 



Bichat has defined life to be organization in action. 



The most productive cow, as the most productive 



man in mental or physical labor, lives an intense 



life. Life, in the sense of motion, — birth and death 



of cells in the organism, — is lived doubly when the 



activity is of double measure. 

 6* 



