The physiology of the circulation in plants : in the lower animals, and in man : being a course of lectures delivered at 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:
1873
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 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.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    enough, not in England, but in Frankfort. It therefore took Harvey some twenty-six years to mature and perfect his views. Harvey left little to be done, but that little fell to the lot of a worthy successor, the renowned Malpighi, who, in 1661, by the aid of the microscope, discovered the capillary circulation, and the presence of blood-globules within the vessels. Harvey's views, thoroughly matured, and sound in warp and woof as they were, met with a determined opposition, and it was only after many an unseemly conflict between really great men, that the blood was allowed to flow quietly in the double channel which he had taken such pains to discover and describe. There is little chance of its changing its course now; and the task which I set myself in the present lectures, is to point out the course which the blood and other nutritious juices pursue, as they meander about in the organic world, now free, now confined; now checked by the presence of valves, now hurried forwards by the pressure of vessels, hearts, and other forces, to which I shall have occasion frequently to allude as the subject becomes more complicated. Definition of the Circulation.—The term circulation, in the present day, is employed in a double sense. In its wider signification, it embraces the course of the nutritious juices through plants and the lower orders of animals ; in its more limited signification, and as applied to man and the higher orders of animated beings, it in- dicates the course of the blood from the heart to the capillaries, and from these back again to the heart. The word circulation literally means a flowing round—a going and returning ; and it is well to bear the original meaning in mind, as we shall find that a single circle aptly represents the circulation in most of the lower animals; a circle with one or more accessory loops, representing the circulation in the higher ones. In man, the chief circle re- presents the systemic circulation—two accessory loops representing the pulmonic and portal circulation. The accessory loops may be increased indefinitely to meet the requirements of any particular case. Circulation in Plants. In plants, the circulation is in its most rudimentary form ; in fact, it is incomplete as a circulation, i.e., as a continuous flow of nutritious juices in a circle. My meaning will be obvious when I remind you, that in trees, the sap flows steadily upwards in spring, and steadily downwards in autumn. The chain is, as it were, broken at both ends. There is, in addition to the upward and downward currents, a certain amount of transfusion, i.e., of cross currents running in the direction of the breadth of the stem ; but the transfusion referred to is trifling when compared with the two principal, and as regards time, interrupted currents.1 In order to ' The nutrient fluids in plants follow certain directions according to the structure and arrangement of the tissues, the locality of the sources of nutrition and of growth, or other actions ; and as regards the elaborated fluid, the move-