of M. Flourens on the'Steroous System. 119 



immediately their animal functions; but it is a question to 

 which we shall have occasion to revert at the conclusion of 

 this Report, even with regard to warm-blooded animals. 



M. Flourens concludes, moreover, from a part of his experi- 

 ments, that what he calls the dispersion or generalization of 

 irritations, or, in other words, general sympathies, are esta- 

 blished by means of the communication among all the nerves 

 of which the spinal marrow is the medium ; but he has not 

 developed this proposition sufficiently to enable us to appre- 

 ciate the I'easonings upon which it rests. 



I come at length to the encephalus ; and it was in this cen- 

 tral part of the system that new lights might be expected from 

 experiments better directed than those of preceding physio- 

 logists. In fact, although Haller and his school made many 

 experiments on the brain, in order to ascertain its vital pro- 

 perties, and the special functions which might be assigned to 

 the different parts of which that complicated organ is com- 

 posed, it must be admitted that these experiments have not 

 given very exact results. The causes of this were, on the one 

 and, the insufficient knowledge possessed at that time of the 

 connexion of the parts of the encephalus and of the directions 

 and communications of their medullary fibres; and on the 

 other, the want of care to isolate them in the experiments. 



When the brain was compressed, for example, it was not 

 known on what point of the interior the compression had acted 

 with the greatest force ; when an instrument was introduced, 

 sufficient care was not taken to examine to what depth and 

 into what organ it had penetrated. 



M. Flourens has, with some reason, made these objections 

 to the experiments of Haller, Zinn and Lorry, and has endea- 

 voured to avoid similar defects by operating principally by 

 the way of ablation ; that is to say, by removing, whenever it 

 was possible, the part whose special function he desired to 

 ascertain. 



In order to convey a more distinct conception of the facts 

 •which he has discovered, we will briefly run over the col- 

 lection and the mutual relations of the parts in question. 



It is now known, especially from the late researches of 

 MM. (iall and Spurzheim, that the spinal marrow is a mass 

 of medullary matter, white on the exterior, gray in the interior, 

 divided longitudinally above and below by furrows, the two 

 fasciculi of which cormnunicate together by means of transverse 

 medullary fil)res ; that it is enlarged at regular intervals ; that 

 it sends out from each enlargement a pair of nerves ; that the 

 medulla oblon^^ata is the superior part of the spinal marrow 

 u»closed within the cranium, which also sends out several pair 



of 



