Page:Popular Science Monthly Volume 7.djvu/265

Rh would sometimes dally about the entrance for a while, but eventually would venture in and push open the closed end of the net; this then closed, and the animalcule was a prisoner. In this way various minute animals—water-bear, daphnia, cyclops, cypris—were seen to enter the chamber of death. No sooner was the victim within, than it manifested alarm, drew in its feet and antennae, and closed its shell. After death the shell unclosed again, displaying the feet and antennae. Not one was ever seen to escape. But, now, how was the observer to know that these animals became the food of the plant? This question occupied the author for several days. If it could be proved that the contents of the bladders were carried directly into the circulation of the plant, the problem was solved. The cells were, in many instances, of a red color, and in all such cases it was observed that the stem at the point where the bladder grew was of the same color. It thus looks "as if a red fluid was carried from the bladders into the main stem, which is not specifically the fact, so far as the observations yet made determine, though the main point, that the contents of the bladders are carried into the circulation, does not seem open to question."

Darwinism by Descent.—Mr. Darwin, many people know, has an hereditary claim to the apostolate of the doctrine of evolution; but Dr. Erasmus Darwin's poems have long ceased to be read by the multitude, and it is not so well known how closely his philosophical creed tallies with that of his accomplished grandson. As an example, however, we take the following passage from "The Economy of Vegetation:"

In a note combating the "prejudices" against the doctrine of spontaneous vital production, Dr. Darwin holds that "there is more dignity in our idea of the Supreme Author of all things, when we conceive him to be the cause of causes, than the cause simply of the events which we see;" and further on intimates the unlikelihood of the larger and more complicated animals being thus produced, as they "have acquired their present perfection by successive generations during an uncounted series of ages."—Iron.

Antiseptics and Infusorial Life.—M. Parmille points out that, according to the investigations of Calvert and others, charcoal, lime, and permanganate of potash, contrary to the received opinion, facilitate rather than hinder putrefactive changes, and actually favor the formation of animalcules. Charcoal, when employed for the purification of water, undoubtedly absorbs offensive gases, and removes dissolved flavoring and coloring matters. But upon living animalcules and their germs it has no destructive effect—if any thing, rather promoting their development. Water containing a known amount of "albuminoid ammonia," when experimentally filtered over animal charcoal, has been found, on analysis, worse than before. M. Danaim found that treatment with charcoal increased the poisonous qualities of putrid blood; the explanation offered being that absorption of the gases dissolved in the liquid removed an obstacle to the development of the infusoria. Permanganate of potash is likewise without effect on living organisms, although it rapidly destroys the dead organic matter. The author considers carbolic, or, better still, cresylic acid, as the only agent which extirpates these animalcules.

Tenacity of Life in the Wheel Animalcule.—It has been asserted that the wheel animalcule (Rotifer vulgaris) may be restored to life by the application of moistturemoisture [sic], after having been dried up, and to all appearance dead. This subject has been investigated by Prof. Leidy, and his results show that there is a very definite limit to the tenacity of life in these minute animals. Two glass slides, containing, beneath cover-glasses, some dirt, exhibited each about twelve living rotifers. After exposure to the sun's rays, the temperature being 80°, for half an hour, the moisture on the slide was dried up. The next morning water was