Page:Popular Science Monthly Volume 21.djvu/728

712 so prominent in all the primitive religions of the world that it has completed the circuit of the habitable globe. As such they form an important item in the evidence to establish the fact that the symbolism employed by the ancient inhabitants of this region was far too refined and abstract to have been the outgrowth of the religious ideas of savage hunters and warriors; and that it bore a close analogy to, if not absolutely identical with, that in use among the nations of the central part of the continent when invaded by the Spaniards." In one of the forms of the figure, the sun is marked with a cross, thus giving new evidence of the universality of that symbol among mankind.

The Bacilli of Tubercle.—The "Medical Press" gives one of the clearest accounts of the experiments by which Dr. Koch has established the bacterial origin of tubercle. In pursuing his investigations, Dr. Koch used material derived both from human and animal sources. Examination of the tuberculous material deposited in various organs led to the discovery of minute organisms possessing all the bacterial characteristics of bacilli, whence the conclusion was formed that those forms of life are invariably present in such deposits. In a multitude of cases of miliary tuberculosis, bacilli in incalculable numbers were encountered in every affected situation, and the conclusion was warranted that they inevitably accompany the development at least of the disease. To demonstrate, however, that they are the cause of the affections, required the accumulation of sufficient actual proof, and Koch's claim to the gratitude of the world rests on the fact that he appears to have made this. Numbers of Guinea-pigs, rabbits, and cats were operated upon, with the result, in every case, of verifying the conclusions which the experimenter had reached. By directly transferring the tuberculous matter from diseased animals to healthy ones, through inoculation, Dr. Koch succeeded in all cases in reproducing the disease. As, however, it was still possible that the contamination might be due to a virus contained in the transferred material, rather than to the presence of microscopic organisms in it, "cultivation" experiments were introduced and conducted on a very exhaustive scale. A pabulum was found in which the bacilli grew and reproduced freely. By repeated sowings in new quantities of the nutritive matter, extending in some cases to six months, a generation of "purified" bacilli was obtained which could not by any possibility be accused of communicating virus. When these organisms were introduced into healthy animals, they never failed to reproduce themselves in incalculable numbers, and to set up all the symptoms of tuberculous infection. Thus, four Guinea pigs were inoculated with bacilli of the fifth generation produced in fifty-four days from tuberculous matter originally derived from a human being. In each case the infected animal sickened and lost flesh, and was found when killed to have strongly pronounced tuberculosis. This took place whatever was the point in the body chosen for the injection of the infective material. When some animals were injected with healthy blood-serum at the same time that others were inoculated with bacilli, the latter sickened and became tuberculous, while the former were not affected. In another series of experiments the sputum of phthisical patients, even after having been thoroughly dried, was found to produce similar effects with the bacilli. Certain conditions seem essential to the development of the bacilli under the ordinary circumstances of communication, and further experiments will bear reference to ascertaining precisely what they are.

Neglect of the Study of Insanity.—In a paper read before the National Association for the Protection of the Insane and the Prevention of Insanity, Dr. Nathan Allen, of Lowell, Massachusetts, calls attention to the neglect in which the study of insanity is left by the medical profession generally. Acknowledging that the study of the functions and disorders of the brain presents more difficulties than any other branch of medical science, but seemingly considering this as only a stronger reason why more attention should be given to it, he finds that in very few instances is insanity mentioned as one of the subjects in the annual circulars of medical schools advertising their lectures. In only three or four schools is there a professorship or course of lectures