THE CARRIERS OF THE HERITAGE 33 



male sperm-cell may not necessarily be entirely 

 excluded from taking part in the formation of the 

 zygote. As a matter of fact, this extra-nuclear part 

 of the sperm-cell sometimes apparently forms the 

 centrosome of the fertilized egg and in consequence 

 may have a hand, as well as the nucleus with the 

 chromosomes, in determining what follows. 



13. THE ENZYME THEORY OF HEREDITY 



It is not unlikely that the key to this whole prob- 

 lem will be furnished by the biochemists and that the 

 final analysis of the matter of the heritage-carriers 

 will be seen to be chemical rather than morpho- 

 logical in nature. 



It has been found that the blood of greyhounds 

 and dachshunds is chemically different, although 

 from a morphological point of view it is apparently 

 identical.- The idea of "individual albumen" or 

 "protein specificity" for each animal of a species, 

 to say nothing of the animals of different species, 

 has been advanced as not improbable. 



Miescher has shown that an albumen compound 

 having only forty carbon atoms, a number by no 

 means unusual, would make possible a million com- 

 binations of atoms or isomers. 



The possibilities in this direction seem to be un- 

 limited if we take into consideration those invisible 

 actuators of chemical processes, the enzymes, which 

 the chemist brings forward with the prodigality of 

 an astronomer dealing in star-dust, to explain dif- 

 ferent chemical .reactions. 



