8 Proceedings of the Royal Physical Society. 
researches. -This method was invaluable for his naked-eye 
dissections, but it did not enable him to determine the con- 
dition of the nervous system in the first month of intra- 
uterine life. He described the general external form of the 
human embryo at the end of the fourth week, but came to 
the conclusion that it then possessed neither brain nor spinal 
cord, their place being taken by a clear fluid. He, however, 
gave an excellent description, with drawings, of the general 
form of the fcetal brain from the twelfth week to the seventh 
month. It is now well known that the external surface of 
the cerebral hemispheres, from about the tenth week to the 
end of the fourth month, present certain. fissures which 
Tiedemann was the first to figure. He was, however, wrong 
in supposing that they were the rudiments of the permanent 
fissures, for, as Professor Cunningham has pointed out, J. T. 
Meckel, a year previously, had correctly described them as 
merely temporary foldings of the cerebral wall. Tiedemann 
does not appear to have investigated to any great extent the 
surface of the hemispheres from the sixth to the ninth month, 
a period during which the development of the fissures and 
convolutions is most active. These omissions, however, were 
to a great extent supplied by Reichart in 1859, Echer in 
1869, and Mihalkovics in 1877.- 
Notwithstanding all that has been done in the comparative 
and developmental anatomy of the cerebral cortex, it is still 
a fruitful field for the earnest investigator. 
The memoir published this year by Professor D. J. 
Cunningham?! shows what valuable and interesting results it 
can still yield. In his memoir, Cunningham has given the 
results of his investigations regarding the development, com- 
parative anatomy, and topographical relations of the principal 
fissures in the Primate brain, together with an able summary | 
and discussion of the work of previous observers. 
It is undoubtedly the most important contribution to the 
morphology of the Primate brain that has appeared for many 
years. Many interesting points, however, still require 
elucidation. Indeed, even now we know practically nothing 
1 Contributions to the Surface Anatomy of the Cerebral BL ce 
Royal Irish Academy, Cunningham Memoirs, 1892. 
