REJUVENESCENCE 151 
moniously a crowd of hive-bees very busy at the 
top of a wayside willow whose upper catkins are 
out. Apart from the catkins and the gorse (which 
does not count), we saw not one opened flower. 
The leaf-buds were just showing on broom and 
briar; the twigs of the larch were gilded a little 
and the birch trees had put on their purple, but 
these were not much more than hints of the reju- 
venescence that we know to be sure and certain. 
' The biology of spring is a book with many 
chapters, and it is but one chapter whose pages we 
would turn to-day. Spring is the time of year par- 
ticularly associated with a capacity that many living 
creatures have of becoming young again—a capacity 
that Man and the higher animals have in greater 
part lost. The whole question has recently been 
brought before serious students of biology in two 
remarkable books by Professor W. M. Child of 
Chicago (Senescence and Rejuvenescence’ and 
Individuality in Organisms’), and it is a profitable 
subject for reflection, not least for those who have 
to-day good reason for finding it difficult to be as 
gladsome as those yellow-hammers, or as rejuvenes- 
cent as these birch trees. In the world for which 
Man is primarily responsible, namely, civilized man- 
kind, domesticated animals, and cultivated plants, 
it is all too easy to find examples of senility—aged 
people who are pathetic as broken harpsichords; 
woe-begone, aged horses and dull-éyed wheezing 
> Chicago University Press, 1915. 
? [bid., 1916. 
