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—.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 
