PROFESSOR TIEDEMANN ON THE BRAIN OF THE NEGRO. 
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substance, as the Negro brain which I dissected had been preserved some time in 
alcohol. 
Meckel and Walter* found the texture of the medullary substance of a Negro 
brain firmer than usual, as tough and firm as it is sometimes found in the brain of 
insane persons. Neither Soemmerring, Camper, Bonn, Caldani, Rudolphi, nor I, 
found this. 
In the internal structure of the brain of the Negro I did not observe any difference 
between it and that of the European ; it seems to me therefore superfluous to give a 
minute description of it. Plate XXXIII. gives an exact representation of a vertical 
dissection of the brain of the Negro Honore', and proves the accuracy of my statement. 
The corpora quadrigemina, the valve of Vieussens, the aqueduct of Sylvius, the 
pineal gland or the conarium, the optic thalami, with the corpora geniculata, the 
corpora striata, the corpus callosum, or coinmissura maxima cerebri, and also the 
eommissura anterior and posterior of the brain, resemble entirely the same parts in 
the brain of the European. 
The glandula pinealis, of a light red colour, of a conical form, lying upon 
the corpora quadrigemina, was fixed to the posterior eommissura by a medullary 
lamella, and was connected by two processes of medullary substance, the pedunculi 
conarii, with the inner side of the thalami optici. In the centre of the pineal gland 
was a fine sandy substance of a yellow colour, called the lapilli glandulse pinealis, or 
the acervulus. Soemmerring likewise found this sandy substance in all the Negro 
brains which he dissected. 
The fornix, with the crura anteriora, arising from the corpora albicantia, the me- 
dullary lamellae of the septum lucidum, the crura fornicis posteriora, with the fimbria 
medullaris, the pedes hippocampi majores, with their round undulated and serrated 
extremity, and the hippocampi minores, occupying the interior of the floor of the 
posterior cornu of the lateral ventricle, showed no difference from that of the Euro- 
pean brain. The lateral ventricles of the brain, two irregular-shaped cavities occu- 
pying the central parts of the three lobes of each hemisphere, consisted of three cor- 
nua, as in the European brain. The anterior cornu ran forwards and inwards in the 
substance of the anterior lobe of each hemisphere. The middle or inferior cornu 
descended to and terminated in the middle lobe. The posterior cornu ran backwards 
and inwards into the posterior lobe of the brain, and ended in a rounded extremity. 
Within each lateral ventricle was a plexus choroideus. 
Are the Nerves of the Negro thicker and larger than those of the European P 
Soemmerring was the first who compared the size of the brain with the thickness 
of the nerves. He says that the nerves on the basis of the brain are somewhat thicker 
* “ Deprehendi substantiam medullarem cerebri in hoc vEthiope duriorem, quam ordinarie in Europads esse 
solet, et ferh tantse tenacitatis, ut in nonnullis hominibus mente captis.” 
