THE UNITY OF NATURE. 273 



That is clear from the fact that no organism is perfect ; 

 even if it does perfectly adapt itself to its environment 

 at a given moment, this condition would not last very- 

 long ; the conditions of existence of the environment 

 are themselves subject to perpetual change, and they 

 thus necessitate a continuous adaptation on the part 

 of the organism. 



Under the title of Design in the Living Organism, 

 the famous embryologist, Carl Ernst Baer, published 

 a work in 1876 which, together with the article 

 on Darwinism which accompanied it, proved very 

 acceptable to our opponents, and is still much 

 quoted in opposition to evolution. It was a revival 

 of the old teleological system under a new name, and 

 we must devote a line of criticism to it. We must 

 premise that, though Baer was a scientist of the 

 highest order, his original monistic views were 

 gradually marred by a tinge of mysticism with the 

 advance of age, and he eventually became a thorough 

 dualist. In his profound work on "the evolution of 

 animals " (1828), which he himself entitled Observation 

 and Experiment, these two methods of investigation 

 are equally applied. By careful observation of the 

 various phenomena of the development of the animal 

 ovum Baer succeeded in giving the first consistent 

 presentation of the remarkable changes which take 

 place in the growth of the vertebrate from a simple 

 egg-cell. At the same time he endeavoured, by far- 

 seeing comparison and keen reflection, to learn the 

 causes of the transformation, and to reduce them to 

 general constructive laws. He expressed the general 

 result of his research in the following thesis : " The 

 evolution of the individual is the story of the growth 

 of individuality in every respect." He meant that 



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