16 HEREDITY AND SEX 



are called the males, or sperm-producing colonies. The 

 other colonies specialize to produce larger germ-cells — 

 the eggs. These colonies are called females or egg-pro- 

 ducing colonies. Sex has appeared in the living world. 



To-day we are only beginning to appreciate the far- 

 reaching significance of this separation into the immor- 

 tal germ-cells and the mortal body, for there emerges 

 the possibility of endless relations between the body on 

 the one hand and the germ-cells on the other. What- 

 ever the body shows in the way of new characters 

 or new ways of reacting must somehow be represented 

 in the germ-cells if such characters are to be perpetu- 

 ated. The germ-cells show no visible modification to 

 represent their potential characters. Hence the classi- 

 cal conundrum — whether the hen appeared before the 

 egg, or the egg before the hen ? Modern biology has 

 answered the question with some assurance. The egg 

 came first, the hen afterwards, we answer dogmati- 

 cally, because we can understand how any change in 

 the egg will show itself in the next generation — in 

 the new hen, for instance ; but despite a vast amount 

 of arguing no one has shown how a new hen could get 

 her newness into the old-fashioned eggs. 



Few biological questions have been more combated 

 than this attempt to isolate the germ-tract from the 

 influence of the body. Nussbaum was amongst the 

 first, if not the first, to draw attention to this distinc- 

 tion, but the credit of pointing out its importance is 

 generally given to Weismann, whose fascinating specu- 

 lations start from this idea. For Weismann, the germ- 

 cells are immortal — the soma alone has the stigma of 

 death upon it. Each generation hands to the next 



