5o5 THE GENERAL PRINCIPLES OF ZOOLOGY 



directly to him that the principle of evolution made no notable 

 advance between Lamarck's " Philosophie Zoologique " and 

 the "Origin of Species" of Darwin. 



Very interesting in connection with the study of Cuvier is 

 the work of his contemporary in Paris, the elder St. Hilaire 

 ( 1 772-1 844), who, though a distinguished naturalist, was even a 

 greater philosopher. He was not so radical in his views on 

 evolution as Lamarck, although he recognized in the environ- 

 ment the cause of variation. His "Philosophie anatomique" 

 was published in 18 18. A most interesting and important en- 

 counter occurred in 1830 at the Academy of Sciences in Paris 

 between St. Hilaire and Cuvier. In the discussion St. Hilaire 

 upheld the unity of structural plan in all animals ; while Cuvier 

 pointed out the different plans of structure in the various 

 types. The former's principle, though correct, was based on 

 facts which were wrong, while the latter cited facts which were 

 correct to support a wrong principle. It is not surprising, then, 

 that Cuvier withdrew from the discussion with the greater glory, 

 and this was another factor in holding back the evolutionary 

 idea in the remainder of the first half of the century. 



As a palaeontologist Cuvier refused to recognize any relation- 

 ship between the animals of the different geological periods; he 

 held that each period was brought to an end by a cataclysm or 

 revolution of nature, and that the fauna of the succeeding period 

 arose by a new creation. Hence it was a matter of great biologi- 

 cal importance when the distinguished English geologist, Lyell 

 ( I 797-1875), published his" Principles of Geology " in 1 830-1833, 

 in which he brought out the lines of evidence for the continuity 

 of action of natural forces in the history of the earth without any 

 violent interruptions. 



Not long after this the cellular structure of plants and animals 

 was noted, and the term protoplasm came into use. We have 

 seen that the word "cell " was used much earlier, but it was not 

 until 1838 that the German botanist, Schleiden (1804-1881 ), ad- 

 vanced the theory that all plants consist of little chambers or 

 cells ; he regarded the cell wall as the important part. In the 

 following year, 1839, the same theory was advanced for animals 

 by the German, Schwann (1810-1882). The word " protoplasm" 

 was first used by Purkinje in 1840 for the substance of which 



