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 1 and 

 Individuality in Organisms 2 }, 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-eyed wheezing 



1 Chicago University Press, 1915. 

 'Ibid., 1916. 



