218 STUDY OF BRAIN'S OF SIX EMINENT SCIENTISTS AND SCHOLARS. 



reduced in the succeeding decades until, in the ninth decade the coefficient sinks 

 to .86. 



Manouvrier has adopted as a good working coefficient : .87, while Nicolucci's 

 is .885. 



Among the notable men discussed in this memoir there are 7 in whom both 

 brain-weight and cranial capacity have been recorded. The resultant coefficients are 

 added in the list. Schumann belongs to the list of the insane, while Gambetta's brain 

 was undoubtedly influenced by the zinc chloride mixture with which the body had 

 been preserved before the autopsy. 



III. 



Before proceeding to a discussion of the results of anatomical examinations of the 

 brains of the notable persons considered in this memoir the writer ventures to devote 

 this chapter to a general exposition of modern views concerning the inter-relations of 

 the brain and the mind, and to lead up to a consideration of the more complex mor- 

 phology of the human brain by briefly tracing the stages of its evolution. In this 

 connection it is necessary to give greater prominence to the post-Darwinian concep- 

 tions of the fundamental importance of morphological investigations of the relations 

 which the human organism bears to other animal forms, more especially the Primates. 

 The demands of evolution have found favorable response in the primate ancestor of 

 man and the general laws of natural selection must be taken into consideration in this 

 connection quite as much as in any other morphological question. Evolution may be 

 said to consist chiefly in the development of means whereby an animal is best adapted 

 to the environment and successfully meets changed conditions by new adaptations — 

 and man is doing much in directing the steps of his own evolution. The cause and 

 effect of human evolutionary progress are both to be found in the story of man's brain- 

 development. Man's competence to deal intelligently with the problem of his exist- 

 ence determines his superiority to all other types. Man is self-conscious to a remark- 

 able degree and capable of selecting and adopting methods for the preservation of his 

 species in a way which no other animal form has yet attained. 



The central nervous system of man and the other vertebrates consists of a sym- 

 metrical apparatus called the cerebro-spinal axis, of which the cephalic extremity in 

 early embryonic life exhibits an intense growth-energy that is indicative of the higher 

 functional potentiality of what is to develop into the brain. The spinal cord with its 

 centrifugal nerves for movements and centripetal nerves for impressions, passes into 

 the skull, becoming slightly enlarged to form the oblongata with its life-centers and 

 cranial nerve roots. At the upper edge of the oblongata a thick band of transverse 

 fibers unites the two lobes of the cerebellum ; this structure is known as the pons. 



