4 Proceedings of the Royal Physical Society. 
T. Tiedentann; writing in 1816, showed the slender 
anatomical basis upon which their theories were based. He 
states that while Gall urged the importance of comparative 
anatomy in the investigation of the functions of the brain, 
he himself only described the nervous system of a worm, 
of a hen, and of a few mammals, and even these few 
imperfectly. 
In 1831, Rolando, an Italian anatomist, gave the first 
clear and accurate representation of the cerebral fissure in 
the human brain, now usually named after him. 
The adult human convolutions are so highly developed and 
so complex in their arrangement, that one cannot be surprised 
at the failure of the older anatomists to detect order in such 
apparent irregularity. It was hopeless to expect any solid 
advance merely by the study of adult human brains. It 
was only through comparative anatomy and development 
that progress in this direction was possible. 
Many of the older anatomists were well aware of the light 
which was thrown upon the structure of the human brain by 
a study of lower forms, and they frequently give illustrations 
of the brains of certain of the domestic animals. In such 
orders as the Carnivora and Ungulata, the general arrange- 
ment of the convolutions differ greatly from that of man; 
their evolution has followed a path of its own, so that the 
attempts to determine their corresponding homologies is 
attended with special difficulties, even if it be not entirely 
futile. In the Primates, however, we have a_ tolerably 
regular evolution from the nearly smooth brain of some of 
the New-World monkeys up to the complex folds found in 
man. Even in the lower Primates, where the convolutions 
are few in number, the general development of the cerebral 
hemispheres and their extension backwards beyond the 
cerebellum indicate a higher type than the convoluted brain 
of many lower mammals. 
It is to Leuret and Gratiolet that we are indebted for the 
first important work on the comparative anatomy of the con- 
volutions, and for perceiving the necessity of an examination 
1 Anatomie und Bildungsgeschichte des Gehirns im Feetus des Menschen, 
Nurnberg, 1816. 
