mediately after the last moult, a number of these were shut up in paper boxes, five to ten in a box, and deprived of food. If, two or three days after confinement in the boxes, any of the larvae were found wandering about, they were fed very sparingly. Nearly all of them lived to complete their transformations. Another lot were, in like manner, put in boxes, but supplied with abundant food. From the latter came sixty-eight females and only four males; from the former seventy-six males and only three females. Five larvæ that were eating vigorously were also taken from their food a day or two before they would have been sated. Of these, four turned out females.
Another experiment was this: Soon after the last moult, twenty larvae were deprived of food for twenty-four hours. Then ten of them were given abundant food again, as long as they would eat. One of these met its death by accident in the chrysalis state, but all the rest became female butterflies. Of the other ten, two died in the chrysalis state; the remainder were males.
Again: Some twenty half-grown larvae of the Vanessa antiopa were accidentally deprived of food. Twelve of them died of starvation, but the remainder completed their transformations. On dissection, these eight all proved to be males. The indefatigable student pushed her investigations further still, for, having found thirty-three larvae of an unfamiliar species, she fed them abundantly, till they would eat no more. The rare and beautiful moth Dryocampa rubicunda made its appearance in due time, and there were twenty-nine females and only two males, the remaining two having either escaped or died. Finally, a lot of the same species of caterpillars were left without food. Some of them were killed by a parasite, others died of starvation, and the seven which survived were all males.
Hydrophobia and the Imagination.—The period of time which elapses between the bite of a rabid animal and the appearance of hydrophobic symptoms varies over a very wide range indeed. The disorder seldom makes its appearance earlier than the eighth clay after inoculation (if inoculation there be); or, again, the virus may be hidden in the wound for weeks, months, or even years. Physicians say that, in most cases, hydrophobia manifests itself in from four to eight weeks after the bite, though there are many authentic cases where the period of incubation extended over eight or nine months, and in one instance even as long as seven years. In this term incubation is implied an hypothesis gratuitously assumed, and scarcely susceptible of direct demonstration. It is found that a patient bitten by a rabid animal passes a certain length of time without manifesting hydrophobic symptoms, and it is supposed that the germs of the disease have been slowly maturing. But, as there is no other disease whose period of incubation is so long or so varying in duration, the hypothesis which traces hydrophobia to animal virus finds no foundation in analogy, and is consequently very weak.
It is, therefore, very natural that medical men should begin to study the whole question anew, and attempt other explanations of this disease. Thus, Dr. D. H. Tuke, whose paper on the "Blanching of the Hair" appeared in our December number, has lately published a work on the "Influence of the Mind upon the Body," and there supports the proposition that hydrophobia is produced solely by the action of the imagination. The author cites cases where, beyond all doubt, hydrophobic symptoms were developed without inoculation. A notable instance is that of a physician of Lyons, named Chomel, who, having aided in the dissection of several victims of the disorder, imagined that he had been inoculated with the virus. On attempting to drink, he was seized with spasm of the pharynx, and in this condition roamed about the streets for three days. At length his friends succeeded in convincing him of the groundlessness of his apprehensions, and he at once recovered. Rush also tells of cases of spontaneous hydrophobia, which arose from no other cause but fear and association of ideas.
A German physician, too, Dr. Marx, of Gottingen, as we learn from the Clinic, is disposed to take this view of hydrophobia, and to regard it as a psychical affection, the result of morbid excitement of the imagination. He is of the opinion that the bite of a mad dog does not, of itself, produce
