364 OF THE CIRCULATION OF BLOOD. 



481. It was formerly supposed, that the movements of the Heart were de- 

 pendent upon its connection with the centres of the Cerebro-Spinal nervous 

 system ; and the experiments of Legallois and others, who found that they 

 were arrested by crushing, or otherwise suddenly destroying, large portions 

 of these centres, appeared to favour the supposition. But it has been shown 

 by Dr. Wilson Philip and his successors in the same inquiry, that the whole 

 Cerebro-Spinal axis might be gradually removed, without any such conse- 

 quence ; which fact harmonizes perfectly with the " experiments prepared for 

 us by Nature," in the production of monsters destitute of these centres, which 

 nevertheless possessed a regularly pulsating heart. It has latterly been the 

 fashion with many, however, to attribute the action of the Heart to the Gan- 

 glionic system ; but of this there is no sufficient evidence. As has already 

 been generally remarked on this subject, the possibility of exciting the action 

 of the heart through the Sympathetic nerve, shows that this may have an 

 influence on its movements ; whilst the great difficulty with which any evi- 

 dence to this effect can be procured, is in itself a sufficient proof, that this 

 influence cannot be nearly adequate to the constant maintenance of this ener- 

 getic function ( 209). It would appear, however, that changes in the Gan- 

 glionic nerves, like strong impressions upon the cerebro-spinal system, may 

 have the effect of impeding or even checking the Heart's action ; for a case 

 has lately been recorded, in which the movements were occasionally checked 

 for an interval of from 4 to 6 beats, its cessation of action giving rise to the 

 most fearful sensations of anxiety, and to acute pain passing up to the head 

 from both sides of the chest, these symptoms being connected, as it proved 

 on a post-mortem examination, with the pressure of an enlarged bronchial 

 gland upon the great cardiac nerve.* It may be surmised, that in many cases 

 of angina pectoris, in which no lesion sufficient to account for death could be 

 discovered, some affection of the cardiac plexus might have been traced on a 

 more careful examination. Brachet has asserted that, by section of the cardiac 

 ganglion, he has caused the movements of the heart to be suddenly arrested ; 

 but this result has not been confirmed by other experimenters. 



482. When the Heart is exposed in a living animal, and its movements are 

 attentively watched, they are seen to be of a peculiarly rhythmical character ; 

 one series following another with great regularity. In an active and vigorous 

 state of the circulation, however, they are so linked together, that it is not easy 

 to distinguish them into periods. A case has recently fallen under the notice 

 of Prof. Cruveilhier, in which the heart was exterior to the chest, having 

 escaped from it by a perforation in the superior part of the sternum ; and his 

 observations upon it may be perhaps regarded as more satisfactory than such 

 as are made after the very severe operation required for the artificial exposure 

 of the organ ; although they are liable to some exception, from the very early 

 age of the subject of them, which had only been born nine hours. His con- 

 clusions will be here adopted, with such additional remarks as are suggested 

 by the experimental researches of others, who have made this question a 

 subject of special attention.! It is universally admitted, that both Auricles 

 contract, and also dilate simultaneously; and that both Ventricles do the 

 same : also that the systole or contraction of the ventricles corresponds with 

 the projection of blood into the arteries, causing the pulse ; whilst the diastole 

 or dilatation of the ventricles coincides with the collapse of the arteries. It 

 is further admitted, that the contraction of the Ventricles, and that of the Auri- 

 cles, alternate with one another ; each taking place (for the most part, at least), 

 during the dilatation of the other. But it is a question, whether there is any 



* Mailer's Archiv. 1841, heft iii.; and Brit, and For. Med. Rev., Oct. 1841. 

 t sp e also another case, recently observed by M. Monod, in Bullet, de 1'Acad. de Med. 

 Fevr., 1843; and Edinb. Med. and Surg. Journ., July 1843. 



