THE STORY OF NINETEENTH-CENTURY SCIENCE 



kingdoms, to the mingled astonishment, delight, and be- 

 wilderment of the closet naturalists. The followers of 

 Linnaeus in. the " golden age of natural history," a few 

 decades before, had increased the number of known spe- 

 cies of fishes to about 400, of birds to 1000, of insects to 

 3000, and of plants to 10,000. But now these sudden 

 accessions from new territories doubled the figure for 

 plants, tripled it for fish and birds, and brought the 

 number of described insects above 20,000. 



Naturally enough, this wealth of new material was 

 sorely puzzling to the classifiers. The more discerning 

 began to see that the artificial system of Linnaeus, won- 

 derful and useful as it bad been, must be advanced upon 

 before the new material could be satisfactorily disposed 

 of. The way to a more natural system, based on less 

 arbitrary signs, had been pointed out by Jussieu in 

 botany, but the zoologists were not prepared to make 

 headway towards such a system until they should gain a 

 wider understanding of the organisms with which they 

 had to deal through comprehensive studies of anatomy. 

 Such studies of individual forms in their relations to the 

 entire scale of organic beings were pursued in these last 

 decades of the century, but though two or three most 

 important generalizations were achieved (notably Kaspar 

 "Wolff's conception of the cell as the basis of organic life, 

 and Goethe's all-important doctrine of metamorphosis 

 of parts), yet, as a whole, the work of the anatomists of 

 the period was germinative rather than fruit-bearing. 

 Bichat's volumes, telling of the recognition of the fun- 

 damental tissues of the body, did not begin to appear 

 till the last year of the century. The announcement by 

 Cuvier of the doctrine of correlation of parts bears the 

 same date, but in general the studies of this great nat- 



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