Researches on the Anatomy of the Brain. 283 



rhoinboideum, for the cerebellum; and successively in the locus 

 niger of Semmering, in the crus cerebri, in the thalamus op- 

 ticus, and in the corpus striatum for the cerebrum. These are 

 what they call the ganglia of reinforcement. 



The numerous nerves which form the crura cerebri and 

 cerebelli (and which they consider as being not less special with 

 respect to the different parts of the hemispheres than the nerves 

 belonging to the organs of the external senses are to them) 

 are continued to the internal surface of the folded or convo- 

 luted membrane constituting the hemispheres of the cerebrum 

 and cerebellum, and which is covered on its external surface 

 with a layer of cineritious matter. From this latter substance 

 arise other white or nervous fibres, which, differing from those 

 before mentioned, pass from the circumference to the centre, 

 and uniting with their fellows, on the median line, form for the 

 cerebellimi the pons Varolii; and for the brain the corpus 

 callosum. These are the parts which Gall and Spurzheim 

 call the commissures of the hemispheres in these organs. 



One of us (Ducrotay de Blainville) has admitted in his ge- 

 neral considerations on the nervous system, that the spinal 

 cord is composed of two lateral columns, each of which con- 

 sists of a principal part formed of white substance, and of grey 

 matter, apparently internal, and of three longitudinal bundles : 

 — one anterior or inferior, and two posterior or superior ; of 

 which one is deep, the other superficial. He has also stated 

 that these two columns are united together anteriorly by a 

 commissure of grey, and posteriorly by a commissure of white 

 substance. 



The views of Blainville differ from those of Gall and Spurz- 

 heim in this ; — that he regards the spinal cord as continuous 

 with all the parts of the brain, which organ he divides into 

 a central part, and a ganglionic part with or without external 

 apparatus. He considers that the central part begins to di- 

 vide into two parts, where the fourth ventricle is formed by the 

 separation of the two superficial posterior bundles, as they 

 proceed onwards to the crura cerebri, which they contribute 

 to form. The result of this he considers to be the uncovering 

 or exposure of the internal cineritious matter, and the forma- 

 tion of the thalami and corpora striata, if these bodies are 

 noi rather to be looked upon as true cerebral convolutions. 

 The larger fasciculi of the cord, or those in which the cineri- 

 tious matter is lodged, directing themselves to the right and 

 left as they advance to the formation of the crura. He even 

 traces the central cineritious substance into the eniinentia; 

 mammillares, and into the substance which closes the third 

 ventricle anteriorly (tlie infundibuhmi). He traces this ven- 

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