THE CURVE OF LIFE 143 



Through more or less critical phases of adolescence 

 it becomes adult. It is a not infrequent achieve- 

 ment to lengthen out the period of mature strength, 

 but sooner or later the edifice begins to crumble. 

 This creature's life is counted in days and that 

 other's in months; we reckon ours in years and the 

 Sequoia's in centuries, but there is for most an 

 ascending and descending curve from the vita 

 minima of the egg-cell (which often dies in a few 

 hours if it be not fertilized) to the vita minima of 

 the outworn creature if the conditions of life admit 

 of senescence, which as a matter of fact is in most 

 cases evaded among wild animals. But part of 

 the fascination of the study of life-histories is to be 

 found in a recognition of the fact that they often 

 differ from one another as different forms of a mel- 

 ody do when the " time "of the various parts is 

 altered, and that this variation in rate is often finely 

 adaptive to particular conditions i.e. is a solution 

 of special problems of life. The morphologists are 

 beginning to discern that one type of skull, or one 

 shape of fish, or one contour of leaf, may be derived 

 from another by supposing a slight deformation 

 let us say, a tilting of the whole architecture, and 

 the idea that we wish to illustrate (it is essentially 

 traceable to the fertile brain of Professor Patrick 

 Geddes) is that one creature's life-history often 

 differs from another's in a change of rate or rhythm, 

 in an elongation of one part of the life-curve and a 

 compression of another. 



A familiar kind of life-history is that into which 



