VI. 



PAHS 



ON THE STITDT OF ZOOLOGY. (A Lecture delivered at the South 

 Kensington Museum, in 1861, and subsequently published by the 

 Department of Science and Art) ............ 94 



t- y x xx viz. 



ON THE PHYSICAL BASIS OP LIFE. (A lay Sermon delivered in 

 Edinburgh, on Sunday, the 8th of November, 1868, at the request 

 of the late Rev. James Cranbrook ; subsequently published in the ^ 

 Fortnightly Review) ................ 120 



VIII. 



THE SCIENTIFIC ASPECTS OF POSITIVISM. (A Reply to Mr. Congrevc's 

 Attack upon the preceding Paper. Published in the Fwtnightly 

 JReview,l869) 147 



IX. 



ON A PIECE OF CHALK. (A Lecture delivered to the Working Men of 

 Norwich, during the Meeting of the British Association, in 1868. 

 Subsequently published in Macmillan's Magazine) 174 



GEOLOGICAL CONTEMPORANEITY AND PERSISTENT TYPES OF LIFE. (The 

 Anniversary Address to the Geological Society for 1862) .... 202 



XI. 



GEOLOGICAL REFORM. (The Anniversary Address to the Geological 

 Society for 1869) 228 



XII. 

 THE ORIGIN OF SPECIES, (The Westminster Review, April 1860) . . .255 



