THE HUMAN SPECIES. 419 



more necessary for the elucidation of the general theory now 

 advanced, if readers were not now very commonly well 

 informed on most of the points brought here under considera- 

 tion. Want of space compelled us, from the beginning, to 

 mass our superabundant materials into groups, which on 

 many occasions may appear too much generalized, and on 

 others marked with repetitions, which sometimes we thought 

 requisite to refresh the memory of the reader. The basis of 

 the questions chiefly investigated was laid in a series of lec- 

 tures on the same subject, read to the Plymouth Institution, 

 between the years 1832 and 1S37. The materials were exclu- 

 sively sought for in scientific researches and profane history ; 

 and the successive discoveries and conclusions of other writers 

 since that period, have, in general, strongly supported the 

 main points of our own convictions, to which we attach no 

 further personal importance than what continued research 

 will disprove, or in due time assent to, when the basis of sev- 

 eral conclusions offered in these pages will have acquired more 

 ample notoriety and consequent solidity. 



