Page:Popular Science Monthly Volume 11.djvu/348

334 that state of the eye persists, and when the animal dies, or is sacrificed, it is seen that this eyeball is smaller than its fellow.

If, now, such an animal were allowed to breed with another—whether operated upon in the same manner or not—it would be seen that young which are born, apparently perfectly healthy, present a few days after birth all the phenomena observed in their changed parent or parents. They have the same smaller eyes, but on both sides; the same ear thickened and enlarged, etc. The only phenomena which they do not show are those which have been transient, the increased heat and the increased sensation which depended upon the increased amount of blood present, etc.

Those young can be made to breed in-and-in for several generations—I have watched them for five generations—and always the same characteristics will be discovered in the young.

If, now, an examination is made of the parent, the first one, it will be seen that the nerve which had been sectioned, or its ganglion which had been extirpated, is not regenerated; while, if an autopsy is made of one of the offspring of any of the subsequent generations, it is seen that they all possess the nerve and the ganglion intact. The acutest or most minute microscopic examinations do not discover any difference between their structure and those of other animals of the same family and species.

If a puncture be made into that portion of the upper part of the spinal cord which anatomists call the restiform body, in Guinea-pigs, it will be seen that the animal presents at once an increased vascularity of the ear on the corresponding side; the ear becomes gorged with blood, chiefly toward the periphery: sometimes in a very short time, indeed, that portion of the ear falls off, destroyed by dry gangrene. I have the record of a case in which the ear was thus partially destroyed in less than nine hours. The eye on the same side becomes larger and protrudes; it protrudes first, and becomes larger in the course of time.

If a pair of Guinea-pigs thus operated upon be allowed to breed, and even if only one parent is thus diseased, the other being healthy, when young are born, these young always present the phenomena observed in the parents; but the phenomena just described only come shortly after their birth. It is seen that their eyeballs increase in size and protrude from their sockets, their ears after a few days become diseased, just like those of the parents, the subjects of experimentation, and drop off, eaten by dry gangrene.

When the parent or parents are sacrificed, and their restiform bodies are examined microscopically, nothing is detected but a cicatrix in the envelopes of the spinal cord, which appear a little thickened at that point, but the nervous tissue itself does not differ apparently from surrounding elements of the same nature and structure. If an examination is also made of one of the young, nothing at all is discovered.