sides an independent system, that there is, if I may thus express myself, a right life and a left life, that the one may exist while the action of the other ceases, and that they are most probably destined reciprocally to supply each other.
It is this which happens in those common sickly affections, where the sensibility and animal mobility, weakened or even entirely destroyed, in one of the symmetrical halves of the body, lose all connexion with what surrounds us; when the man is, on one side, scarcely, more than vegetable, while, on the other, he retains all his right of animality in the remaining sensation and motion. These partial paralyses in which the median line is the end and origin of the faculty of feeling and moving, certainly cannot be so regularly observed in animals, which, like the oyster, have an irregular exterior.
Organic life, on the contrary, makes one uniform system where all is coordinate, where the functions of one side cannot be interrupted, without necessarily producing disorder in those of the other. The liver diseased on the left influences the state of the stomach, on the right; if the colon of one side ceases to act, that of the other cannot continue its action; the same blow which stops the circulation in the great venous truncs and the right portion of the heart, destroys it also in the left portion and the great arterial truncs of this side, &c. Whence it follows, that, supposing all the organs of internal life of the one side to cease their functions, those of the opposite side necessarily remain inactive and death must ensue.
This assertion, however, is only general; it holds good only in the totality of organic life, and not in its separate phenomena; some, in fact, are double and may supply each other, of which the kidneys and lungs afford an example.
I shall not search for the cause of this remarkable difference which in man and some other animals, distinguish
