CHAPTER VIII. 



WHAT IS A SPECIES?— VARIOUS DEFINITIONS AND 

 OPINIONS. 



What are Species? — Their Numbers and Importance. — In the 



previous chapter reference is made to the great importance of 

 the idea of species to the study of natural history, and in the 

 following chapter an attempt will be made to answer the 

 question, " What are species? " 



Bronn, in 1849, published a list of all the then known 

 fossil species.* The list comprised 2050 names of plants, 

 24,300 names of animals. When Zittel wrote his Paleontol- 

 ogy f he quoted Giinther's estimate of 320,000 species of liv- 

 ing animals, and 25,000 fossil animals, already described. 

 Of this 350,000 species of animal organisms, now known to 

 science, what is it in each case which the naturalist observes, 

 and names and enumerates as a species? 



Ernst Heinrich Haeckel, in his " History of Creation," in- 

 sists upon the importance of the idea of species, as follows : 

 " Even now all the important fundamental questions as to the 

 history of creation turn finally upon the decision of the very 

 remote and unimportant question, ' What really are kinds or 

 species?' The idea of organic species may be termed the 

 central point of the whole question of creation, the disputed 

 centre, about the different conceptions of which Darwinists 

 and anti-Darwinists fight." :}; 



Linne held that there are as many different species as there 



* H. G. Bronn, "Index Paljeontologicus," etc. 3 vols. Stuttgart, 1848-49. 



f K. A. Zittel, " Handbiich der Palaeontologie," vol. i. Miinchen, 1S76. 



X E. H. Haeckel, "The History of Creation; or, The development of the 

 ■earth and its inhabitants by the action of natural causes; a popular exposition 

 of the doctrine of evolution in general, and of that of Darwin, Goethe, and 

 Lamarck in particular; the translation revised by E. R. Lankester," 2 vols. 

 New York, 1SS3. Vol. I. p. 42. 



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