PKEFACE. 



THE aim of this work is to set forth the general truths of 

 Biology, as illustrative of, and as interpreted by, the laws 

 of Evolution: the special truths being introduced only so 

 far as is needful for elucidation of the general truths. 



For aid in executing it, I owe many thanks to Prof. 

 Huxley and Dr. Hooker. They have supplied me with in- 

 formation where my own was deficient ; * and, in looking 

 through the proof-sheets, have pointed out errors of detail 

 into which I had fallen. By having kindly rendered me 

 this valuable assistance, they must not, however, be held 

 committed to any of the enunciated doctrines that are not 

 among the recognized truths of Biology. 



The successive instalments which compose this volume, 

 were issued to the subscribers at the following dates: No. 

 7 (pp. 180) in January, 1863; No. 8 (pp. 81160) in 

 April, 1863; No. 9 (pp. 161240) in July, 1863; No. 10 

 (pp. 241320) in January, 1864; No. 11 (pp. 321 400) in 

 May, 1864; and No. 12 (pp. 401 476) in October, 1864. 

 London, September 2QM, 1864. 



* Gross misrepresentations of this statement, which have been from time 

 to time made, oblige me, much against my will, to add here an explanation of 

 it. The last of these perversions, uttered in a lecture delivered at Belfast by 

 the Rev. Professor Watts, D.D., is reported in the Belfast Witness of Decem- 

 ber 18, 1874 ; just while ft third impression of thia work is being printed from 



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