Page:Popular Science Monthly Volume 6.djvu/390

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THE POPULAR SCIENCE MONTHLY.

as now published by Mr. Thomson in the Chemical News, it appears that eggs, when the shells are intact, can only be decomposed by one, two, or all of three different agencies. The first of these agencies is the putrid cell. This may be developed in the egg, however effectually the shell is protected against spores from without, or the diffusion of gases; it is generated from the yelk. Certain gases have the effect of retarding or preventing its growth, as carbonic dioxide and coal-gas, but it is promoted by oxygen. One egg, which had for 118 days remained in an atmosphere of oxygen, was found to be decomposed entirely by "putrid cell;" the yelk had expanded, and was thoroughly mixed up with the white, and the contents emitted a putrid smell. The atmosphere, once pure oxygen, on analysis showed only a fraction of one per cent, of that gas, while the amount of carbonic dioxide was 95 per cent.

The second agency in decomposition is a vibrio, which in all cases comes from without, and never exists originally in the egg. Whole eggs that remain dry, exposed to the atmosphere for any length of time, are never attacked by this animalcule; but, if the outside of the shell becomes moist, the vibrios floating in the atmosphere fall on it and develop in the contents. The third agency is a fungus, the Penicilium glaucum, which exists suspended in the atmosphere. If whole eggs are placed in a constant draught of air, but few will be attacked by this fungus; but, if they are left in a stagnant atmosphere, the floating spores will settle on the shell, and send their long fibres through it into the contents. This fungus cannot grow in an atmosphere of carbonic dioxide, but in oxygen its growth is most luxuriant. In some cases of decomposition by the penicilium the egg was found to appear as if it had been perfectly coagulated by boiling. The filaments of the fungus branch about in immense numbers in all directions, twisting and twining into each other among the contents.

 

Experiments on the Living Human Brain.—Some experiments, made by Dr. Bartholow, of Cincinnati, on the living human brain, having drawn upon him the sharp censure of sundry professional journals, he has offered an explanation of his conduct in the British Medical Journal. "The person on whose brain the experiments were made was," he writes, "hopelessly diseased with a rodent ulcer, which had already invaded the dura mater; life could not have lasted much longer in any case. The patient herself consented to have the experiment made. The experiment consisted in applying electricity to the brain, as in Terrier's researches, and it was believed that fine insulated needles could be introduced without injury, for the following reasons: The brain has been successfully incised to discharge pus. Portions of the brain have been lost without fatal injury to the patient. Then, the faradic current was used, which has no electrolytic action. In the present case it was the ulcer, not the puncture of the needles, that caused death." Dr. Bartholow concludes his letter as follows: "Notwithstanding my sanguine expectations, based on the facts above stated, that small insulated needle-electrodes could be introduced without injury into the cerebral substance, I now know that I was mistaken. To repeat such experiments with the knowledge we now have, that injury will be done by them, would be in the highest degree criminal. I can only now express my regret that facts which I hoped would further, in some slight degree, the progress of knowledge, were obtained at the expense of some injury to the patient."

 

The Struggle for Existence.—Mr. Buckland recently fought a pitched battle in the Round Pond, Kensington Gardens, with the innumerable hosts of a crustacean parasite that was destroying the fishes. Having learned that there was something wrong at the pond, Mr. Buckland went there to make a reconnoissance, and found, at one point, some little distance from the bank, a dense "cloud of fish." Having waded into the midst of them, he discovered that the supply-pipe, through which fresh water was admitted to the pond, was nearly choked up. The fish wanted fresh water, evidently. He took up with a landing-net one or two of those that were most sickly, and found them literally covered with parasites. Various means were tried for removing the parasites, the most expeditious way being