XIX 

 THE CURVE OF LIFE 



TO Huxley it seemed that one of the most 

 significant characteristics of living crea- 

 tures was their "cyclical development." From a 

 microscopic egg-cell an embryo plant develops; 

 the ovule becomes a seed, the seed a seedling; by 

 insensible steps there is formed a large and varied 

 fabric of root and stem, leaves and flowers. But 

 no sooner has the edifice attained completeness 

 than it begins to crumble. The grass withereth 

 and the flower thereof fadeth, and soon there is 

 nothing left but the seeds, which begin the cycle 

 anew. It is, Huxley said, "a Sisyphaean process, 

 in the course of which the living and growing plant 

 passes from the relative simplicity and latent 

 potentiality of the seed to the full epiphany of a 

 highly differentiated type, thence to fall back to 

 simplicity and potentiality again." So is it also 

 among animals. The microscopic egg-cell divides 

 and redivides, and there is built up an embryo. This 

 may develop steadily and directly into the likeness 

 of its kind; or it may give rise to a quite divergent 

 phase a larva of some sort such as caterpillar or 

 tadpole, which by and by undergoes metamorphosis 

 and gets shunted on to the direct line of ontogeny. 



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