38
reproductive powers of the germs become increased and their numbers multiply. At present, two factors seem to be recognised as determining the severity of the attack due to inoculation, viz., the vitality and reproductive power of the germs, and the number introduced.
It would be idle to speculate further on the ideas thus suggested. Can it be that the specific fevers of the human race have each their own bacillus? May the exhaustion of the menstruum serve as an explanation of their termination in individual cases; and the loss of reproductive powers be the cause of the termination of an epidemic? May we hope in each of them some day to inoculate a mild form of the disease which will preserve the individual from a more severe attack? Whatever answers may in the future be given to these and similar questions, the definite results already arrived at in the two diseases which have formed the subjects of investigation cannot be ignored, and can only be set aside by showing them to be exceptional instances. I feel bound to affirm that, in my judgment, the course of inquiry pursued has been in strict accordance with Harvey's principle of questioning Nature by way of experiment; and I cannot but believe that the answers do really present what may be called "Laws of Nature."
I have done. But I cannot conclude this Oration without a reference, however brief, to the memorial
