DARWIN'S DISCOVERIES 23 



been effected. Every attempt to show by experiment 

 that a new character can be acquired by the stock in 

 this way, and show itself by heredity alone when the 

 modifying adapting conditions are removed has com- 

 pletely failed. 



On the other hand, Darwin himself and his followers 

 have made almost endless experiments and observations 

 on plants and animals, establishing facts as to structure 

 and the relation of special kinds of living things to their 

 surroundings which can only be explained on the sup- 

 position that Darwin's theory is true in detail ; that is to 

 say, not merely that the kinds of animals and plants have 

 arisen from previous kinds by natural descent that 

 supposition is much older than either Darwin or Lamarck 

 but that the method by which the transformation has 

 been brought about is (a) the occurrence in every genera- 

 tion of every animal and plant of minute variations in 

 every, or nearly every, part, and (b} the continual selection 

 in the severe struggle for existence of those individuals 

 to grow to maturity and reproduce, which happen to 

 present favourable variations, which variations are accord- 

 ingly transmitted to the next generation, and may be 

 intensified, so far as intensification is of value, in each 

 succeeding generation. 



A book full of observations and reflections about the 

 structure, habits, and mode of occurrence and geography 

 of a great number of plants and animals is Darwin's 

 Journal of Researches, published in 1845, and now re- 

 published as A Naturalist's Voyage. In order to know 

 very minutely the differences and resemblances between 

 all the kinds or species of one group of living things 

 Darwin studied for eight years the " cirrhipedes," the name 

 given to the sea-acorns and ships' barnacles which occur 

 in all parts of the world, some living on rocks, some on 

 the backs of turtles, others on whales, on the feet of birds, 



