MODERN BIOLOGY 475 



besides which it may often happen that the strongest males spur or butt one 

 another to death, with the result that afterwards comparatively weak speci- 

 mens win a place among the females. In support of his theory Darwin placed 

 the male intelligence at a radically higher value than the female. He over- 

 looked the fact that the females also exercise an important function, which 

 likewise demands intelligence, in the care and protection of their offspring. 

 His theories on this subject nevertheless won strong support in certain liter- 

 ary quarters; it is well known that, among others, Strindberg has referred 

 to them with enthusiasm. 



In connexion with the last-mentioned work Darwin published another 

 book, entitled Expression of the Emotions in Man and Animals, in which he 

 records a large number of facts regarding emotions in man and the animals, 

 which he had amassed and compiled and to which he, of course, applies 

 his theory of selection and descent. Further, in his later years he published 

 a number of works on special subjects that are in part extremely valuable. 

 Among these may be mentioned his work on insectivorous plants — it was 

 he who first pointed out that these plants really digest and resorb the im- 

 prisoned animals — another on the climbing organs of plants, in which these 

 organs are described with exhaustive thoroughness and from numerous fresh 

 points of view, and finally a work on cross- and self-fertilization in plants, 

 as also a book of fundamental importance wherein he continues Sprengel's 

 work, which he had rescued from oblivion, and paves the way for modern 

 heredity-research. In the year before his death he also published a brief but 

 ingenious work on the formation of vegetable mould through the action of 

 worms, in which he establishes, on the strength of a large number of ob- 

 servations and experiments, the important role played by these animals as 

 re-formers of the earth's surface, in that a considerable portion of the earth's 

 outer layers passes through their intestinal canal and is thereby influenced 

 physically and chemically — facts which research had previously failed to 

 observe, but which have latterly been fully confirmed. 



Darwin s general opinion of life 

 During the greater part of his life Darwin devoted himself to his own par- 

 ticular field of research more thoroughly than most other scientists. He never 

 went in for teaching nor took up any other public appointment, while owing 

 to his ill health he had to give up social life, with the result that his activi- 

 ties became more and more confined to biological speculations and experi- 

 ments. This may explain why he embraced with such intensity, but also 

 with such limitations, the theories he set up. He was but little influenced 

 by other natural-scientific tendencies, eventually losing interest even in gen- 

 eral cultural problems. In his youth he had been interested in art, poetry, and 

 music, but in his old age even these lost their attraction for him. True, by 

 way of diversion he used to have novels read to him, requiring only that 



