Page:Popular Science Monthly Volume 6.djvu/205

Rh Timothy Lewis, who has been for some time in Calcutta, carrying on, in concert with Dr. D. Cunningham, important sanitary investigations, has, among other things, directed his attention to the vitality of tapeworm germs in cooked meat. He proved, first, that tape-worm germs are undoubtedly killed by exposure for five minutes to a temperature of 135°-140° Fahr.; and then, with a view of ascertaining also how far they would be likely to experience such a temperature in the ordinary process of meat-cooking, he made other important observations having considerable interest for us. Dr. Lewis found that when legs of mutton had been put into the boiler almost as soon as the water, their central temperature averaged 140° Fahr. by the time the water around them had reached the boiling-point, and that, after the water had boiled for five minutes, the internal temperature of the legs of mutton which had remained in the boiler had on an average reached 170°. This is a practical method of dealing with the question which those skeptical dreamers who talk of the "protective influence of lumps" would do well to imitate.

After this I may perhaps be deemed fully justified in quoting two very typical experiments for the consideration of those who stave off their belief in the occurrence of "spontaneous generation" either by relying upon insufficient reasons for doubting the influence of boiling water, or because of their following Pasteur, Cohn, and others, in supposing that certain peculiar Bacteria-germs are not killed except by a brief exposure to a heat of 227° or 230° Fahr. For, even if we could grant them these limits, of what avail would the concession be toward staving off the dreaded admission of the occurrence of "spontaneous generation," in the face of such experiments as those which follow?

—A strong infusion of turnip was rendered faintly alkaline by liquor potassse, and to this a few separate muscular fibres of a codfish were added. Some of this mixture was introduced into a flask of nearly two ounces' capacity. Its neck was drawn out and afterward hermetically sealed by the blow-pipe flame, while the fluid within was boiling. When thus closed the flask was about half full of fluid. It was then introduced into a digester which was gradually heated, and afterward kept at a temperature of 270°-275° Fahr., for twenty minutes, though it seems also well to point out that, if we include the time taken for the water of the digester (in which the closed flask was immersed) to attain this heat, and also again to cool down to 230 Fahr., this flask was exposed to temperatures above 230° Fahr. for one hour, as I myself carefully noted at the time. When withdrawn from the digester the closed flask was kept at a temperature of 70-80° Fahr. for eight weeks, and during part of this time it was exposed to the influence of direct sunlight. After it had been ascertained that the flask was free from all crack or fault, its neck was broken, in order that its contents might be examined. The reaction of the fluid was found to have become decidedly acid, and it had a sour though not