OF ARTS AND SCIENCES. 245 



of man are larger than those of monkeys when compared with the 

 dimensions of the spinal cord of the cerebellum, medulla oblongata, or 

 optic lobes ; that, in the proportions of most of the parts just referred 

 to, the seals, after the monkeys, are among the animals which ap- 

 proach nearest to man ; and in the proportions of the brain to the 

 spinal cord are nearer than these, and stand next to man. 



His work on the development of the human brain has become clas- 

 sical. This was the result of patient labor, extending through several 

 years, and has for its object a complete description, from his own dis- 

 sections, of the changes which the brain undergoes from early foetal 

 life to the end of gestation. The gradual evolution of parts is de- 

 scribed for each month of intro-uterine life. In addition to the de- 

 velopmental phases which the brain presents under such circum- 

 stances, he has given a comparative exposition of its structure in the 

 different classes of vertebrates, in order to show how far the for- 

 mation of this organ in the human foetus goes through, in different 

 embryonic periods, stages which correspond with, or resemble, the 

 mature brains of the lower animals. These resemblances, which had 

 been partially recognized by Meckel, were far more satisfactorily de- 

 monstrated and illustrated by Tiedemann. This work was published 

 in 1816, and treats of a subject then new to physiological science; and 

 out of Germany the ideas which it taught were generally received 

 with ridicule by the physiologists of his time. To-day they are 

 almost universally adopted. Better microscopes, and a more exten- 

 sive use of them than was possible in his time, have added much 

 to our knowledge of the development of the brain. No one work 

 relating to the same subject presents better results than those con- 

 tained in his monograph, and to this day it is the best authority. 



In 1836 he presented to the Royal Society a memoir on the brain 

 of the Negro compared with that of the European and the Orang- 

 outang. In this he discusses the question, whether there is any essen- 

 tial difference between the brain of the Negro and that of the Euro- 

 pean, and whether the former resembles that of the Orang more 

 closely than the brain of the European does. His desire to substan- 

 tiate everything by the accumulation of facts is conspicuous in this 

 memoir. His results are based upon a comparison of the weio-hts of 

 more than fifty brains, and the measurement of the internal capacity of 

 two hundred and sixty-eight crania of different nations. From the 

 data drawn from these sources, he concludes that, although the Negro 



