The physiology of the circulation in plants, in the lower animals, and in man : being a course of lectures delivered at the Surgeons' Hall to the president, fellows, etc. of the Royal College of Surgeons of Edinburgh, in the summer of 1872 / by J. Bell Pettigrew.

  • Pettigrew, James Bell, 1834-1908.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: The physiology of the circulation in plants, in the lower animals, and in man : being a course of lectures delivered at the Surgeons' Hall to the president, fellows, etc. of the Royal College of Surgeons of Edinburgh, in the summer of 1872 / by J. Bell Pettigrew. Source: Wellcome Collection.

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    The cells, as has been already pointed out, are for the most part unipolar, with a sprinkling of bipolar ones (Fig. 151 D, p. 312). They contain a nucleus and one or more nucleoli (A, B, C, D). In some cases and under certain conditions they present a granular appearance (E). Analogy inclines me to believe that the ganglia and nerve-cells just described are to be regarded as nerve-centres or diminutive brains. In this I agree with Winslow, Winterl, Johnstone, Unger, Lecat, and Peffingers. They assist in regulating and co-ordinating the movements of the heart, and preside over its nutrition. This view, if taken in connexion with the vital properties inhering in involuntary muscles, in part accounts for the rhythmic movements of the heart when the organ is cut out of the body, when it is severed from its nervous connexions, and when it is deprived of blood, unless such as is found within its walls. It is the blood within the muscular parietes of the heart which keeps it alive and enables it to move rhythmically. Why does the Heart act Rhythmically? To this question no satisfactory reply can be given in the present state of science. The older observers attributed the phenomenon to various and extraordinary causes. Stahl, e.g. declared the movements of the heart to be under the guidance of the anima or soul. Sylvius, the head of the chemical sect, traced them to an effervescence caused by a mixture of the old and alkaline blood with the acid chyle and acid pancreatic juice; while Descartes referred them to a succession of explosions occurring within the heart due to a generation of steam. Willis, with a greater show of reason, attributed the movements of the heart to the cerebellum and the eighth pair of nerves. To these Boerhaave added two additional causes, viz. the action of the blood of the arteries on its fibres, and of the venous blood on the surface of its cavities. The hypothesis of Willis explained how the heart is subject to the storm of the passions, but it did not explain how the heart beat in the anencephalous foetus (foetus devoid of brain and spinal cord), or in animals whose brain and spinal cord were crushed or removed. Still less did it explain how the