No. 606] 



BIOLOGICAL ENIGMAS 



343 



duction of any desired amount of this substance; and a 

 simple calculation shows that the chromatin of the human 

 zygote has sufficient volume to contain about one quad- 

 rillion (10^^) molecules the size of that of oxygen.-*" 



In order that the enzj-mes of the germ-cell should be 

 able to determine the form of the mature organism, they 

 must have the power to govern (1) the physical and chem- 

 ical properties of specific tissue material, (2) the posi- 

 tion of specific tissues, (3) the size of these tissues and 

 (4) their form. Since the physical properties of any 

 piece of matter depend upon its chemical constitution, 

 and since any chemical change can be regulated by 

 catalysis, the mere presence of a specific catalyzer in a 

 favorable mixture is sufficient to determine the produc- 

 tion of matter of any possible variety, in any possible 

 amount. It is always necessary to assume that tlie his- 

 tory of an organic system is such as to have provided it 

 with the raw materials necessary to its activities. If this 

 is not the case, the system naturally perishes of '^star- 

 vation. ' ' 



The most primitive form of cell-division involves noth- 

 ing more than reduplication, and this is the law of mul- 

 tiplication of the germ-plasm. Driesch-*^ argues that to 

 explain the reproduction of a nuclear "machine" which 

 determines development, we must postulate another ma- 

 chine to carry out the operation, and so on ad infinitum. 

 The nature of the autocatalytic process, however, shows 

 that this conclusion is in error, since pure autocatalysis 

 would tend to bring about an exact qualitative reproduc- 

 tion of any given plane or linear mosaic of specific units. 

 In a nutritive medium such a mosaic would tend to grow 

 in all of its parts by the deposition of similar substance. 

 Primitive nuclear division (as, e. g., in the Protista) may 

 depend solely upon the physical instal)ility of coHoidal 

 particles greater than a certain size, but it can hardly be 



diameter of the germ-cell nucleus is .05 mm., and (2) that the molecules 

 fill only one-sixth of the total volume of the nucleus. 



<8Driesch, H., "The Science and Philosophy of the Organism," 190S, 2, 



