94 THE CRITERIA OF LIVINGNESS 



to indicate, however, is that the correlation of chemical 

 processes which makes continued self -maintenance possible, 

 naturally leads on to growth, and that growth naturally leads 

 on to division or reproduction. This remains true though 

 our ignorance of the physiology of cell-division is confessed. 



It is possible, however, to take another step. It is char- 

 acteristic of organisms to multiply, and they multiply by 

 division, separating off a fragment, a group of cells, or a 

 single cell. This brings us face to face with development 

 the power that a part has of growing and differentiating 

 until it has literally reproduced the whole.- Development 

 is the making visible of the latent potentialities the intrinsic 

 manifoldness of the liberated fragment, or sample, or cell ; 

 and while the development of a fertilised egg-cell into an 

 organism remains to us one of the wonders of the world, 

 we venture to suggest that the development may be profitably 

 thought of as a continuation of the processes which are always 

 going on to preserve the specific organisation in good repair. 

 Every gradation between the two may be found in the 

 phenomena of regrowth or regeneration of lost parts. But 

 when we associate this capacity of development with growth 

 and multiplying we see that we may unite them all in the 

 conception of cyclical development, which Huxley was wont 

 to emphasise in his discussions of the characteristics of living 

 creatures. 



From a microscopic egg-cell an embryo plant develops j 

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

 steps there is fashioned 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 



