5 o6 SCIENCE PROGRESS 



with the powers of nourishing the tissues of the body. The 

 crude blood was then supposed to pass from the liver to the 

 right side of the heart whence most of it percolated through the 

 septum to the left ventricle. This process to some extent refined 

 the blood. In the left auricle in diastole, air was sucked into the 

 heart ; which brought about two results, the cooling of the 

 innate heat of the heart and the generating of vital spirits. 

 The vital spirits were carried by the blood in the arteries to all 

 tissues and organs to enable them to perform vital functions. 

 The blood with its vital spirits that went to the brain was 

 supposed to undergo a sort of distillation or refining for the last 

 time, with the result that the animal spirits were separated 

 from it and carried to the body by the nerve-trunks. The 

 animal spirits in motor nerves made muscular movements 

 possible, those in sensory nerves were productive of sensations. 



We still speak of animal spirits, of " a man of spirit " and so 

 forth ; and the expression " the vapours of alcohol " or " fumes of 

 drugs ascending to the brain " are based on the analogous ascent 

 of vital spirits from the heart to the brain. As recently as the 

 time of Queen Anne (1708) the Daily Conrant advertised a per- 

 fume as efficacious because " it increases all the spirits, natural, 

 vital, and animal." This is exactly in the Galenical order. 



The point of interest for us in all this about spirits is that 

 thus early we have glimmerings of the notion of innervation, 

 the agent of which is spirits ; for the animal spirits of Galen are 

 the nerve-impulses of to-day. It will be noticed, however, that 

 there is in this ancient doctrine of spirits some sort of latent 

 distinction between powers of absorbing nourishment, of 

 expressing vitality, and of conferring movements. The modern 

 advance on this is that not even the absorption of nourishment 

 is outside of innervation. The growth of the ideas of innervation 

 centred, as might have been expected, round the power to 

 arouse movements in muscles, in fact around motor innervation 

 only. 



The problem which so agitated the physiologists of the 

 eighteenth century had not arisen in Galen's time, namely 

 whether muscles contracted of themselves, for instance after all 

 their nerves were cut (doctrine of Inherent Irritability), or 

 whether all their irritability was conferred on them through 

 their nerves, that is from outside, the so-called doctrine of the 

 Neurologists. 



