96 PHYSIOLOGY 



John Ingen-Housz 



Excerpts from Experiments upon vegetables 



Reprinted from Experiments upon vegetables, 

 London, 1779. 



I was not long engaged in this in- mass of the atmosphere, contributes to 

 quin- (the relationship of air and sun to render it more fit for animal life; that 

 plants— Ed.) before I saw a most impor- this operation is far from being carried 

 tant scene opened to my view: I ob- on constantly, but begins only after the 

 served, that plants not only have a fac- sun has for sometime made his appear- 

 ulty to correct bad air in six or ten ance above the horizon, and has, by his 

 days, by growing in it, as the experi- influence, prepared the plants to begin 

 ments of Dr. Priestley indicate, but that anew their beneficial operation upon 

 they perform this important office in a the air, and thus upon the animal cre- 

 complete manner in a few hours; that ation which was stopped during the 

 this wonderful operation is by no darkness of the night; that this opera- 

 means owing to the vegetation of the tion of the plants is more or less brisk 

 plant, but to the influence of the light in proportion to the clearness of the 

 of the sun upon the plant. I found that day, and the exposition of the plants 

 plants have, moreover, a most surpris- more or less adapted to receive the di- 

 ing facult\' of elaborating the air which rect influence of that great luminan,'; 

 they contain, and undoubtedly absorb that plants shaded by high buildings, 

 continually from the common atmos- or growing under a dark shade of other 

 phere, into real and fine dephlogisti- plants, do not perform this office, but, 

 cated * air; that they pour down con- on the contran.', throw out an air hurt- 

 tinually, if I may so express myself, a ful to animals, and even contaminate 

 shower of this depurated air, which the air which surrounds them; that this 

 diffusing itself through the common operation of plants diminishes toward 



* Air deprived of its principle of inflammability. Oxygen was not known 

 then as it is now. Dcphlogisticated air is good air and, as we now know, con- 

 tains enough oxygen for respiration. — Ed. 



