OF CULLEN. 587 



circulation, secretion, nutrition, sensation, and 

 muscular motion, including the generation of 

 animal heat, are owing to the agency of a subtile 

 and elastic principle* inherent in the medullary 

 substance of the brain ; and which he termed the 

 nervous fluid, or the nervous power, that this fluid 

 or power is the prime mover in the animal body, 

 and determines the activity of all the organs, whether 

 voluntary or involuntary, that as it appears only in 

 the living, and disappears entirely in the dead state 

 of the body, it must be regarded as the vital prin- 

 ciple, and that it regulates not only the various 

 degrees of muscular strength, but the quantity,, 

 quality, and distribution of the fluids, with every 

 variety of temperament. (Materia Medica, p. 55, 

 88, 99.) 



In accordance with this hypothesis, he taught 

 that all medicinal and morbific agents exert their 

 influence primarily on the nervous system, and 

 not through the medium of the blood, as main- 

 tained from the days of Hippocrates down to the 



* But if caloric, in some of its forms, be the cause of all elas- 

 ticity, it must be the very same principle which Cullen terms the 

 nervous fluid, and describes as the prime mover in the animal 

 economy. Moreover, although he maintained that cold, mias- 

 mata, and all other causes of disease, produce their effects by 

 operating immediately upon the nervous system, and not through 

 the medium of the blood, he does not fail in his faithful and 

 generally accurate descriptions of disease, to inform us, that in 

 all the varieties of malignant fever, small-pox, scurvy, dysentery, 

 and tetanus, the blood exhibits a disorganized state, and coagu- 

 lates very imperfectly or not at all. 



