The germ theory applied to the explanation of the phenomena of disease : the specific fevers / by T. Maclagan.

  • Maclagan, T. J. (Thomas John), 1838-1903.
Date:
1876
Catalogue details

Licence: Public Domain Mark

Credit: The germ theory applied to the explanation of the phenomena of disease : the specific fevers / by T. Maclagan. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    25/282 (page 13)
    ii.] The change produced in the oxamide by a small quantity of oxalic acid results in the formation of a large quantity of that acid; and the only limit to the continuance of this change is the quantity of the oxamide. This large reproduction of oxalic acid during a process set agoing by its own presence in minute quantity, has been sup- posed to be analogous to the mode of formation of contagium ; and to be sufficient to demonstrate that a substance capable of exciting a change in others may, during that change, be multi- plied indefinitely, independently of the presence of germs7. As thus stated by the opponents of the germ theory the argument seems a most telling one. Taking the broad fact that oxalic acid is reproduced in large quantity during a chem- ical change induced by itself, we cannot fail, at first sight, to be struck by the analogy which seems to obtain between this process, and that wdiich results in the formation of contagium during the course of the specific contagious diseases. On more minute examination, however, the analogy fails entirely. For what is oxamide? It is simply oxalate of ammonia, less two equivalents of water. When oxalate of ammonia is heated in a retort, oxamide is formed: when oxamide is boiled with a strong acid or alkali, oxalate of ammonia is produced. The decomposition of the one readily results in the forma- tion of the other. The composition of oxalate of ammonia is -N H4 O, C2 03 8; that of oxamide is the same, minus two equivalents of water, or N H2 C2 02. The constituents of oxa- mide axe thus the radical amide, NH2, and C2 O.,, which is the ladical of oxalic acid; and the change which takes place duiing the decomposition of oxamide simply consists in the sharing between these two radicals of two equivalents of water • thus N H2 C2 02+ 2TIO = NH40, C2 03 or oxalate of am- Murchison in ‘Transactions of Pathological Society of London ’ for 1871; stoU^;Tnethe °ld “ bGCaUSe ^ SimplGr ^ m°re