246 PROCEEDINGS OF THE AMERICAN ACADEMY 



brain in some respects (as, for example, in its breadtli as compared 

 with its length, as also, to a slight extent, as regards its size and 

 weight) is inferior to that of the European, in most others it is not so, 

 and that the difference between the brain of the Negro and that of the 

 Orang is far greater than between the former and the European. He 

 concludes his memoir with a general survey of the contributions of 

 Negroes to literature and science, and expresses full confidence in 

 their capacity for progress in civilization, and believes that, but for 

 the depressing influence of the African slave-trade, this capacity might 

 soon become manifest. 



He commenced a " Complete Treatise on Human Physiology," but 

 this was never finished. The first two volumes, which are merely 

 introductory, are remarkable for their broad and philosophical views, 

 and are based upon a very extensive knowledge of comparative anat- 

 omy and physiology. The importance of these last sciences to the 

 progress of human physiology no one more fully appreciated than he. 

 Among other monographs published by him, those on the following 

 subjects may be mentioned : — 



On the Nerves of the Uterus. 



On the Ophthalmic Ganglion and the Ciliary Nerves of Animals. 



On the Comparative Anatomy of the Hearts of Fishes. 



On the Anatomy of Anencephalous and Acephalous Monsters. 



This last is a very complete monograph, and comprises the results of 

 very numerous dissections. 



His monograph on the structure of the Echinoderms was one of his 

 most celebrated works, and received the prize of the French Institute 

 in 1811. It was not published until 1816. 



In forming an estimate of the value of Tiedemann's labors, we must 

 not judge him by the standard of the present day. It is nearly twenty 

 years since his period of activity ended, and in the mean while physi- 

 ology has undergone a complete revolution. When he was retiring 

 from the field of active life, the importance of the test-tube, the bal- 

 ance, and the microscope were only beginning to be appreciated. 

 Liebig had just commenced his researches in physiological chemistry, 

 and histological discoveries had only begun to influence the scientific 

 world. Nevertheless, we are very largely indebted to him for the 

 impulse which, during the last thirty years, has advanced physi- 

 ology to the rank which it now holds among the sciences. Tie- 

 demann's influence is to be attributed quite as much to the spirit 



