288 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



title of" fever destroyer." At any time swamp waters may be 

 purified by introducing the Elodea^ after which they become 

 fit abodes for fishes and other animal life. Sitzber. Bonn^ 

 p. 62. 



THE EFFECT OF THE PEESSUEE OF THE AIR UPON HUMAN 



LIFE. 



Dr. Jourdanet, who has for many years resided at Mexico 

 as a practicing physician, has had occasion to observe the 

 eflfect upon human life of different conditions as to altitude 

 above the sea, and has recently published, in two large vol- 

 umes, an important work on this subject. In this work he 

 has grouped together facts collected from all portions of the 

 globe, and with much sagacity and honesty has been able to 

 achieve something exact with respect to the effect of altitude 

 upon human life. The fundamental principle adopted by him 

 has been that the true nature of the efiect of exterior influ- 

 ences is better shown by the diseases that they cause than by 

 the healthfulness which they favor in man. After studying 

 the influence of the oxygen of the atmosphere upon the blood, 

 and even the diminution of temperature with increasing 

 height above the sea, and, finally, the influence of the hy- 

 ofrometric state of the air, he combines all these considera- 

 tions in the general study of climatic influence of high al- 

 titudes, and confirms the following law of Paul Bert for 

 pressures of 30 inches and less: "The exercise of that faculty 

 which animals possess of appropriating to themselves the ox- 

 ygen of the atmosphere is controlled by the density of this 

 gas, as found in the circumambient air." Death is not, then, 

 caused by the prevailing low atmospheric pressure. It is the 

 oxygen itself, or its pressure, exclusive of the general baro- 

 metric condition, that controls the result; so that if from a 

 pressure of 30 inches of air, one third of which is oxygen, we 

 pass to another atmosphere with a pressure of 15 inches of 

 air, two thirds of which is oxygen, we have conditions equally 

 favorable to human life, since, for equal volumes of air, we find 

 equal volumes of oxygen. La Aeronaute^ Sept.^ 1875, 261. 



LUBBOCK ON THE SENSES OF INSECTS. 



Much has been written on the use of the antennae of insects. 

 That they serve as organs of touch all are agreed; but it is 



