98 



PHYSIOLOGY 



it was exposed to the sun during an 

 hour and a half, in whicli time the air 

 was so much corrected that a candle 

 could burn in it. "^riie same effect was 

 obtained from a sprig of a vine, and 

 that of a camomile plant, and from 

 some rushes. 



A nmstard plant was put in a jar; 

 the stem was cut off on a level with the 

 orifice of the jar; the jar was then in- 

 Ncrted in an earthen pan containing 

 some water to keep the plant alive, and 

 placed over-night in a room; next morn- 

 ing the air of the jar was found much 

 fouled, so as to extinguish the flame of 

 a w^ax-taper; its test by Abbe Fontana's 

 method, was 1.98, 2.87, 3.83. 



It was then exposed to the sun, and 



examined again after a quarter of an 

 hour, and found already somewhat 

 corrected, for its test was then 1.97, 

 2.84, 3.79. 



The jar was again put in the open 

 air, when, after standing one and one- 

 half hours in the sun, the air was found 

 to be remarkablv corrected, for now its 

 test was 2.01, 2.25, 3.24. 



I'he jar was again replaced in the 

 sun; when it had been exposed during 

 three complete hours, the air was so 

 much improved as to be better than the 

 common air at the time, for its test was 

 1.95,2.211/2,2.20. 



The test of the common air was at 

 that time, by Abbe Fontana's method, 

 1.96; 2.25; 3.261/2. 



QUESTIONS 



1. What is the modern name of the proc- 

 ess upon which Ingen-Housz seemed 

 to be engaged in this article? 



2. Reproduce here the equation repre- 

 senting the process. 



3. With what end product of this process 

 is the author most concerned? With 

 what raw material? 



4. When considering plants and animals 

 together, would jou say that oxygen 

 was a waste product of the process? Ex- 

 plain. 



5. Evaluate this statement. Animals re- 

 spire all the time. Plants respire only 

 at night. During the daytime, they 

 carry on photosynthesis. 



6. Did Ingen-Housz think that the air 

 given off by plants at night was harm- 

 ful? What is the modern view? 



7. From your knowledge of scientific 

 method, point out one major fallacy 

 of Ingen-Housz' experiments. 



N.B. Ingen-Housz was born in 1730 and died in 1799. He was the phy- 

 sician to Emporcr Joseph II. His work on light and photosynthesis is his 

 greatest contribution. 



