Experiments on animals / by Stephen Paget.

  • Stephen Paget
Date:
1906
Catalogue details

Licence: In copyright

Credit: Experiments on animals / by Stephen Paget. Source: Wellcome Collection.

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    capillaries, but the vevpa of Aristotle, It was believed that the blood, between the smallest arteries and the smallest veins, made its way through “ blind porosi- ties ” in the tissues, as water percolates through earth or through a sponge. The first account of the capil- laries is in two letters {De Pulmonibus, i66i) from Malpighi, professor of medicine at Bologna, to Borelli, professor of mathematics at Pisa. In his first letter, Malpighi writes that he has tried in vain, by injecting the dead body, to discover how the blood passes from the arteries into the veins :— “ This enigma hitherto distracts my mind, though for its solution I have made many and many attempts, all in vain, with air and various coloured fluids. Having injected ink with a syringe into the pulmonary artery, I have again and again seen it escape (become extravasated into the tissues) at several points. The same thing happens with an injection of mercury. These experi- ments do not give us the natural pathway of the blood.” But, in his second letter, he describes how he has examined, with a microscope of two lenses, the lung and the mesentery of a frog, and has seen the capil- laries, and the blood in them :— “ Such is the divarication of these little vessels, coming off from the vein and the artery, that the order in which the vessel ramifies is no longer preserved, but it looks like a network woven from the offshoots of both vessels.” He was able, in a dead frog, to see the capillaries ; and then, in a living frog, to see the blood moving in them. But, in spite of this work, it took nearly half a century before Harvey’s teaching was believed by all jxien—Tantum consuetudo apud omnes valet.
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