, 



who considers a diminution of the energy of the brain to be the essential 

 character of fever ? 



It is well known that the difference of the length of the neck, and, con- 

 sequently, the greater or lesser degree of vicinity of the heart and brain, 

 give a tolerable just measure of the intellect of man, and of the instinct of 

 the lower animals ; the disproportionate length of the neck has ever been 

 considered as the emblem of stupidity. 



In the actual state of our knowledge, is it possible to determine in what 

 manner arterial blood acts on the brain ? Are oxygen or caloric, of which 

 it is the vehicle, separated from it by|this viscus, so as to become the prin- 

 ciple of sensation and emotion, or do they merely preserve it in the de- 

 gree of consistence necessary to the exercise of its functions ? What is to 

 be thought of the opinion of those chemists who consider the brain, as a 

 mere albuminous mass, concreted by oxygen, and of a consistence vary- 

 ing in different persons, according to the age, the sex, or the state of 

 health or disease ? Any answer that one might give to these premature 

 questions, would be but a simple conjecture to which it would be diffi- 

 cult to give any degree of probability*. 



CXLVII. Of the theory of syncope. If we consider the action of the 

 heart on the brain, we are naturally led to admit its necessity to the main- 

 tenance of life, and to deduce from its momentary suspension, the theo- 

 ry of syncope. Several authors have attempted to explain the manner in 

 which their proximate cause operates, but as not one of them has gone 

 upon facts ascertained by experience, their explanations do not at all 

 agree with what is learnt from observing the phenomena of these dis- 

 eases. 



To satisfy one's self, that the momentary cessation of the action of the 

 heart and the brain, is the immediate cause of syncope, one need but 

 read, with attention, the chapter which Cullen, in his work on the prac- 



* The connexion which exists between the functions of the heart and those of the 

 brain, are not only manifest in their healthy relations, but also in their disordered ac- 

 tions. PORTAL, BRICHETEAU and TESTA had pointed out this connexion in the diseases 

 of these organs, and more recently Dr. CRAISIE has contended for its importance, al- 

 though some contemporary puthologists have denied its existence. This pathologist, 

 after stating his experience on the subject, draws the following inferences from it : 



" 1st. It is quite obvious, that several maladies of the heart, such as ossification of the 

 left side, or of the artery connected with it ; ossification of the mitral valve ; of the semi- 

 lunar valves ; ossification of the apertures either auriculo-ventricular, or aortic, have a 

 tendency to terminate in extravasation within the cranium, producing apoplexy, paraly- 

 sis, or a comatose state terminating in death. 



"2d. It is by no means difficult to see how these effects in the cerebral organ result 

 from an irregular and disordered action of the heart. The difficulty which the blood 

 experiences in passing either, 1st. through the auriculo-ventricular opening ; 2d. the 

 aortic orifice ; 3d. along the aorta, necessarily produces a stagnation and congestion ; 

 1st. in the pulmonary veins ; 2d. in the pulmonary artery ; 3d. in the right side of the 

 heart. The effect of this is to retardpr impede very remarkably the return of the blood 

 from the cerebral veins, and consecutively either to distend them, to rupture them, or 

 to occasion an effusion of the serous part of the blood, as we find in other examples of 

 obsti-ucted venous circulation." (Edin. Med. Journ. JYo. 74.) Dr. Craigie has, how- 

 ever, omitted to mention the influence of active enlargement of the left side of the 

 heart in causing apoplexy, owing to the increased impulse or determination of blood 

 which is thus produced, and to which the brain is most obnoxious. This and every oth- 

 er form of connexion of disease of the heart with apoplexy can only be viewed as occa- 

 sional occurrences, the former states being by no means necessarily followed by the lat- 

 ter. Copland. 



