SECT. III.] PROPERTIES OF THE VIS NERVOSA. 399 



convulsed by the stimulus of the electric spark. ^ The vis nervosa 

 of the spinal cord, and of the nerves given off by it, remained in a 

 case after atheroma of the medulla oblongata, pons varolii, and 

 entire cerebellum had destroyed the connection between the 

 spinal cord and a dropsical brain.^ Moreover, the vis nervosa 

 not only continues in the spinal cord and nerves long separated 

 from their connection with the brain, but exists in nerves that 

 never had any connection with the brain whatever. This is 

 proved by the histories of acephalous foetuses, which lived 

 during the whole period of intra-uterine life, were nourished, 

 increased in growth, and when bom evinced no obscure signs 

 of vitality, without having a brain, and by the sole vis of the 

 nerves and spinal cord, if the latter was not also defective. 

 Animals which have nerves but no cerebrum also demonstrate 

 the same fact. 



From these facts it is obvious, that the vis nervosa remaining 

 in the nerves after the severance of their connection with the 

 brain, must be considered as the cause whereby the heart was 

 able to continue its movements, in the experiments instituted 

 by Haller and other distinguished men, after the brain and 

 cerebellum were destroyed, the head cut off, and even all the 

 nerves of the heart divided. For the stimulus of the blood, alter- 

 nately flowing into the cavities of the heart, irritated its nerves 

 still endowed with vis nervosa, although separated from the 

 brain, and thus excited it to alternate contractions. But 

 another interpretation has been given to these facts; and espe- 

 cially by Haller, namely, that it is manifest, that if the heart's 

 action continues after decapitation, or destruction of the whole 

 cerebrum and cerebellum, the cardiac movements are not in 

 connection with the nerves, but with an irritability innate in 

 the heart, and not dependent on the nerves. But the fallacy 

 in this conclusion is most manifest, since it can only be fairly 

 inferred that the heart can continue its action without the brain 

 and spinal cord, but not without its own nerves, which, although 

 entirely separated from the brain, are still united to the heart, 

 and still as endowed with the vis nervosa, and as impatient of a 



' Caldani excited movements of paralysed muscles by the electric spark. Consult 

 Haller's Bib. Anat. 



2 De Haen. Rat. Med. Contin., torn, iii, section i, cas. ix, the dissection of which 

 I performed before my lamented teacher. 



