The graft theory of disease : being an application of Mr. Darwin's hypothesis of pangenesis to the explanation of the phenomena of the zymotic diseases / by James Ross.
- Date:
- 1872
Licence: Public Domain Mark
Credit: The graft theory of disease : being an application of Mr. Darwin's hypothesis of pangenesis to the explanation of the phenomena of the zymotic diseases / by James Ross. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![ment clouds of these scales were seen to arise from his head and face, the heavier settling on his clothes, while the lighter danced in the sunlight. This observation made a dee]) impression upon me at the time, but I did not recognise its full significance until I read Professor Tyndall’s experiments with the electric beam. If, then, contagious diseases cast off innumerable epithelial cells and particles, and if these cells and particles are found floating in the atmosphere, the spread of contagious diseases are as satisfactorily accounted for by the theory under consideration, as by the one which regards con- tagium particles as independent organisms. The next step we must take is to adduce evidence to show that the particles concerned in the produc- tion of contagious diseases are only alive as parts of a living body ; and since, as has already been seen, the direct or experimental evidence upon this point fails us, our only alternative is to develop, as far as possible, the indirect or analogical evidence. Is there, then, any order of facts in the whole field of biology, to show that particles apparently so insig- nificant, and which are living only in the sense of being detached portions of a living body, can initiate changes so extensive as those which occur in the zymotic diseases ? The events which succeed the union of the germ-cell and the sperm-cell m ordinary repro- duction will strike every one as more or less analogous to the case in hand, and a closer exami-](https://iiif.wellcomecollection.org/image/b21904649_0047.jp2/full/800%2C/0/default.jpg)
