22 GENERAL PRINCIPLES OF ZOOLOGY. 



Lamarck (Jean Baptiste de Monet, Chevalier de Lamarck, 

 born in Picardy, 1744, died, Professor at the Jardin des Plantes, 

 1839) taught that on the earth at first organisms of tlie simjjlest 

 structure arose in tlie natural way through spontaneous generation 

 from non-living matter. From these simplest living creatures have 

 developed, by gradual changes in the course of an immeasurably 

 vast space of time, the jiresent sjjecies of plants and animals, 

 without any break in the continuity of life upon our globe; the 

 terminal point of this series is man ; the other animals are the 

 descendants of those forms from which man has developed. 

 Lamarck, in accordance with the then prevailing conceptions, 

 regarded the animal kingdom as a single series grading from the 

 lowest primitive animal up to man. Among the causes which may 

 influence the change and perfecting of organisms, Lamarck 

 emphasized particularly use and disuse; the girafEe has obtained a 

 long neck because by a special condition of life he was compelled 

 to stretch, in order to browse the leaves on high trees; conversely, 

 the eyes of animals which live in the dark have degenerated from 

 lack of use into functionless structures. The direct influence of 

 the external world must be unimportant ; the changes in the sur- 

 roundings (Geoffrey St. Hilaire's le monde amhient) must for the 

 most part act indirectly upon animals by altering the conditions 

 for the use of organs. 



Evolution vs. Creation. — Lamarck's ingenious work remained 

 almost unnoticed by his contemporaries. On the other hand there 

 arose a violent controversy between the defenders and the 

 opponents of the evolution theory when [1830] Geoffrey St. Hilaire 

 in a debate in the Academy at Paris defended against Guvier the 

 thesis of a near relationship of the vertebrates and the insects, and 

 set up the proposition that the latter were "vertebrates runninii- 

 on their backs." The conflict ended in the complete overthrow of 

 the theory of evolution; the defeat was so complete that the 

 problem vanished for a long time from scientific discussion, and 

 the theory of the fixity of species again became dominant. This 

 error was occasioned by many causes. Aliovc all, the theorv of 

 Geoffrey St. Hilaire and Lamarck was rather a clever conception 

 than founded on abundant facts; besides, it had in it as a funda- 

 mental error the doctrine of the serial arrangement of the animal 

 world. Opposed to this stood Gnvier's great authority a.nd his 

 extensive knowledge, the latter making it easy for him to show 

 that the animal kingdom was nnide up of separate co-ordinated 

 groups, the types. 



