GROWTH OF THE CEREBRAL CORTEX 253 
while the cortical thickness in the latter is much greater (by 
about 25 per cent). 
Prosimiae and primates. The following table (table 6) is 
summarized from a paper by Marburg (’12) and shows for some 
species of the prosimiae and primates the total cortical thickness 
measured at four representative localities (gyri centralis, fron- 
talis, temporalis et occipitalis). The average values were taken 
by me. 
TABLE 6 
Thickness of the cerebral cortex at several localities in monkeys, as presented by 
Marburg (12). Averages are calculated by me 
AVERAGE 
CEN- FRON- TEM- occi- <a ae a Tir 
SPECIES TRAL TAL PORAL | PrTaL | Of the | Of the 
GYRUS | GYRUS | GYRUS | GYRUS four three 
locali- | locali- 
ties ties 
mm. mm. | mm. mm. mn. mm. 
SUMMIa SAV TUS Ae ood aan bream koh cles aoe Bolu | Bose | B23} 2.84 
iv lobatesn(Sps))eenern melee ae SMM lS ||| Seon mlerioe eae som|memultes 
Semnopithecus masicus...........-4.... B03) | as I DB ahaa) |) oO: || Beis} 
IMPVCOGUE TANTS a6 a bade ne Gaswoeeosonuek PAL | DITO) |) PTGS |W) ah 288) |) A BXO) | BE 
Cynocephalus hamadryas...............| 2.97 | 2.70 | 2.03 | 1.35 | 2.26 | 2.57 
Abeleshmilo erie ame, tae ck a noe totus ae ee 2.97 | 2.84 | 2.48 21D) 
Remiunevianiisn7e sss ots ee ee ee SON Onl le 1Oy ele Oden ele G2 ele oll 
This table also suggests that, in the order of monkeys, the 
average thickness of the cortex varies so that those which have 
the greater brain weight have also the greater thickness of the 
cerebral cortex, but the brain weights are not available for 
comparison. 
V. THE THICKNESS OF THE CEREBRAL CORTEX IN MAN 
Man. There are scores of papers giving the measurements of 
the thickness of the cerebral cortex in man, but they are diverse 
in the techniques used for preparing the material, in the locali- 
ties selected for measurement, and also in the manner of meas- 
urement. The results published before 1891 were all summa- 
rized by Donaldson (’91), but the table is not reproduced here as, 
- owing to the lack of the information necessary for the interpre- 
tation of the values found, it has mainly an historical interest. 
