504 THE GENERAL PRINCIPLES OF ZOOLOGY 



There were many speculative writers in the eighteenth cen- 

 tury who theorized about evolution, but in most instances their 

 conjectures were so wild and their surmises had so broad a 

 foundation in medieval fable and classical mythology that 

 their works did nothing for the advance of the science ; they 

 are interesting from the historical point of view, but need not 

 detain us here. 



Passing from the eighteenth to the nineteenth century, one 

 of the first and most important zoologists we meet is Lamarck 

 (1744-1829), whom we have already noticed in the chapter on 

 theoretical biology. There has been much diversity of opinion 

 as to his ability, but to-day he is very generally recognized to 

 have been a man of real genius. He was interested at first in 

 botany, became intimately acquainted with Buff on, and in 1766 

 wrote an article in which he expressed his disbelief in the 

 theory of spontaneous generation and his belief in the immuta- 

 bility of species. This article was not published until 1 794 ; 

 whether he still entertained the same belief at that time is a 

 matter of doubt ; at any rate he took up the study of zoology at r 

 that period, and his views soon changed. In 1802 he intro- 

 duced the term Biology, and it is interesting to note that the 

 German naturalist, Treviranus ( 1 776-1 837), suggested the word 

 in the same year. Lamarck's work on animals led to his 

 making several improvements in the system of classification. 

 He introduced the terms Vertebrata and Invertcbrata and 

 organized the groups Arachnida, Crustacea, and Annelida. He 

 further recognized that all animals cannot be arranged in a 

 linear series from the lowest to the highest, but rather in a 

 system of treelike branching ; this was the first attempt at 

 such an arrangement, which has since been greatly elaborated. 

 His most important written work was the " Philosophic Zoolo- 

 gique," which appeared in 1809. In this he unfolded his theory 

 of evolution, which of course necessitated the mutability of 

 species ; this, he concluded, was brought about by the action of 

 the environment on the organism ; the necessity for a part gave 

 rise to it; it was then developed through use and inherited by 

 succeeding generations. This theory he held practically un- 

 altered until the time of his death ; its similarity to the theory 

 of Erasmus Darwin has been repeatedly pointed out, but th 



