400 Intelligence and Miscellaneous Articles. 



greedy absorber and a carrier of oxygen, but also an oxidizing agent, 

 and that it is by its means that the substances which enter the 

 blood from the food, setting aside those which are either assimilated 

 or excreted by the kidneys, ars reduced to the ultimate forms of 

 carbonic acid and water, as if they had been burnt in oxygen. 



21. In illustration of the functions of cruorine, I would refer, in 

 conclusion, to the experiment mentioned in § 10. As the purple 

 cruorine in the solution was oxidized almost instantaneously on being 

 presented with free oxygen by shaking with air, while the tin-salt 

 remained in an unoxidized state, so the purple cruorine of the veins 

 is oxidized during the time, brief though it may be, during which it 

 is exposed to air in the lungs, while the substances derived from 

 the food may have little disposition to combine with free oxygen. As 

 the scarlet cruorine is gradually reduced, oxidizing thereby a portion 

 of the tin-salt, so part of the scarlet cruorine is gradually reduced in 

 the course of the circulation, oxidizing a portion of the substances 

 derived from the food or of the tissues. The purplish colour now 

 assumed by the solution illustrates the tinge of venous blood, and a 

 fresh shake represents a fresh passage through the lungs. 



L. Intelligence and Miscellaneous Articles. 



INFLUENCE OF HEAT-FORCE ON VEGETABLE LIFE. 

 BY GEORGE BENTHAM, PRESIDENT OF THE LINN^AN SOCIETY*. 



T CAXKOT conclude my remarks upon the recent progress of 

 -*- biological science without alluding to the modern discovery of 

 the dynamical theory of heat, or equivalence of heat and force — a 

 wonderful theory, which the lectures of Tyndall have rendered prac- 

 tically clear even to the unscientific mind, but which, nevertheless, 

 it is difficult to follow in all its details without feeling a certain 

 bewilderment of the brain. I may refer to Dr. Carpenter's article 

 " On the Application of the Principle of Conservative Force to 

 Physiology," in the ' Quarterly Journal of Science ' for January 

 and April of the present year, for a general review of the influence 

 of this force on vegetable and animal life, and, for a more popular 

 summary, to the graphic sketch of the relation of the sun to life, 

 contained in the closing portion of Prof. Tyndall' s twelfth lec- 

 ture. But in this summary occur the following passages, which, 

 however correct in regard to the great principle they are intended 

 to illustrate, might yet, I think, without explanation, lead the 

 ordinary reader into considerable error with regard to some great 

 biological facts, and upon which therefore, on account of the high 

 standing of the distinguished author, and the general circulation 

 which the work must command, I think it necessary to offer a few 

 observations. 



" The earth's atmosphere contains carbonic acid, and the earth's 



surface bears living plants ; the former is the nutriment of the 



latter. The plant apparently seizes the combined carbon and 



oxygen, tears them asunder, storing up the carbon, and letting the 



* From the Anniversary Address, delivered May 24, 1864. 



