THE HUMAN SPECIES. 12 T 



How much remains still to be done, may be further 

 instanced in the mental faculties, which have been even 

 more neglected ; neither have they noticed religious 



organization and fullness of development. But this is only 

 attained by gradual steps. At the earliest period that it is 

 cognizable to the senses, it appears a simple fold of nervous 

 matter, with difficulty distinguishable into three parts, and 

 having a little tail-like prolongation, which indicates the 

 spinal marrow. In this state it perfectly resembles the 

 brain of an adult fish ; thus assuming, in transitu, the form 

 that is permanent in fish. Shortly after, the structure be- 

 comes more complex, the parts more distinct, the spinal 

 marrow better marked. It is now the brain of a reptile. 

 The change continues by a singular motion. The corpora 

 quadrigemina, which had hitherto appeared on the upper 

 surface, now pass towards the lower ; the former is their 

 permanent situation in fishes and reptiles, the latter in birds 

 and mammalia. This is another step in the scale. The 

 complication increases ; cavities or ventricles are formed, 

 which do not exist in either fishes, reptiles, or birds. 

 Curiously organized parts, such as the corpora striata, are 

 added. It is now the brain of mammalia. Its last and 

 final change is wanting, that which shall render it the brain 

 of Man, in the structure of its full and human development. 

 But although, in this progressive augmentation of organized 

 parts, the full complement of the human brain is thus 

 attained, the Caucasian form of Man has still other transi- 

 tions to undergo, before the complete chef d'oeuvre of nature 

 is perfected. Thus, the human brain successively assumes 

 the form of the Negroes, the Malays, the Americans, and 

 the Mongolians, before it attains the Caucasian. Nay more, 

 the face partakes of these alterations. One of the earliest 

 points where ossification commences, is the lower jaw. 

 This bone is therefore sooner completed than any other of 

 the head, and acquires a predominance which it never 

 loses in the Negro. During the soft pliant state of ihe 

 bones of the skull, the oblong form which they naturally 

 assume, approaches nearly the permanent shape of tho 



