SECT. III.] PROPERTIES OF THE VIS NERVOSA. 389 



has known how to assign these animal faculties without the 

 aid of a nervous system : nay more ; nature has granted even 

 to certain irritable vegetables a sort of sensation and motion, 

 analogous to the motion and sensation of animals, and that 

 without a nervous system. 



SECTION III. WHAT IS UNDERSTOOD BY THE VIS NERVOSA, AND 



WHAT ARE ITS GENERAL PROPERTIES. 



All the functions of the nervous system are as dependent 

 upon its structure and nature, as the accurate indication of time 

 upon the construction of the chronometer. In inquiring into 

 the structure of the nervous system, our senses, however well 

 assisted by the microscope, teach us nothing more than that the 

 principal portion of it, the medullary, is supplied with numerous 

 arterial and venous capillaries, distributed both to the cerebrum 

 and to the nerves. We cannot say, however, that the whole is 

 vascular, because, after the most successful injection of a 

 coloured fluid into the cortical substance of the brain, and the 

 medullary substance of the brain and nerves, the larger portion 

 remains uninfected; and this is not vascular, but inorganic in a 

 manner, being composed of a mass of very small globules as seen 

 under the microscope, not unlike the globules seen to compose the 

 whole organism of polypes and zoophytes, and the pulp of fruits. 

 Albinus long ago refuted the doctrine of Ruysch,^ that every 

 part of the body is composed of nothing but vessels, by showing 

 that in bone, cartilage, muscle, nerve, and in the medullary and 

 cortical portions of the brain, there was a large proportion of 

 matter which was not vascular. Malpighi seems to intimate the 

 same opinion, with reference to the cortex of the brain, and also 

 the medulla,^ when he says, that he found no organisation in 

 the cortex, except in the sanguiferous vessels with which it is 

 pervaded ; and if a parenchymatous substance should be at any 

 time assigned to the brain, in which the vessels and other 

 organised products might be supported, the cortex is the proper 

 part, inasmuch as it would seem to resemble moss mixed with 

 deep coloured clay. In another epistle, however, he tries to 

 show that it is glandular. 



If any reliance is to be placed on our senses, the structure 



> Adnot. Acad., lib. iii, cap. i ; et lib. i, p. 52. 



' Epist. ad Fracassatum de Cerebro. In Bib. Anat. Mangeti, 



