GROWTH 103 



which are elaborated into protoplasm, it is, of course, 

 obvious that the chemical nature of the available 

 food supply will have a marked influence upon the 

 growth of both plants and animals. Careful ex- 

 periments seem to show that growth is advanced 

 most in the presence of abundant nitrogenous com- 

 pounds, next in the presence of fats, and least in that 

 of carbohydrates. Growth may also be greatly 

 accelerated by various chemical stimuli. Thus it 

 has been found that many poisons, deadly to the 

 organism when in any considerable concentration, 

 yet stimulate growth when in extreme dilution. 

 Mercuric chloride, strychnine, cocaine, ether, and 

 many other poisons act in this way. 



