Respiration of Plants and Animals. 21 



Art. VIII. — A Neiu Point of Resemblance in the 

 Respiration of Plants and Animals. 



By James Jamieson, M.D. 



[Read 13th June, 1878.] 



Respiration in plants consists just as it does in animals, in 

 the inhalation of oxygen and the exhalation of an approxi- 

 mately equivalent quantity of carbonic acid. This process, 

 though masked under ordinary circumstances by the more 

 active deoxidizing action of the green parts of the plant, 

 seems, according to recent investigations, to be constantly 

 going on, and to be as necessary to the life and health of the 

 plant as of the animal. The deoxidizing action of the green 

 organs, carried on by means of the chlorophyll contained in 

 them, is tolerably well known, and consists in the splitting 

 up of carbonic acid into oxygen and carbonic oxide. The 

 oxygen is wholly, or in great part, set free in the air, while 

 the carbonic oxide seems to enter into some kind of com- 

 bination with the chlorophyll, as a preliminary to the 

 formation of more complex compounds, and especially of the 

 various hydro-carbons. A series of investigations on this 

 point are contained in a paper by Adolf Baeyer, in the 

 Gheniisches Centralhlatt, 1871, pp. *27 — 38, and also translated 

 in a slightly condensed form in the Journal of the Chemical 

 Society, 1871, pp. 331 — 341. My object is not, however, to 

 enter into any details on this process, which is one of 

 assimilation, but rather to consider the mechanism of 

 respiration in the proper sense of the word, which is essen- 

 tially associated with processes of regressive metamorphosis. 

 Some observations which I have made seem to throw lig^ht 

 on the chemistry of the respiratory function in plants, and I 

 desire therefore to report the result of them, incomplete and 

 fragmentary as they are. 



For the proper understanding of the particular point on 

 which I wish to lay stress, and which, after consulting the 

 best accessible authorities, I am led to believe is new, or at 

 least very little known, it will be necessary to mention cer- 

 tain facts connected with the better-known chemistry of the 

 function of respiration in the higher animals. The red colour 

 of blood is due to the presence in it of large numbers of 



