424 Baker . — Quantitative Experiments on 
endure a larger dose of formaldehyde without poisonous effects than they 
otherwise would ; also, that the plants can become accustomed to a certain 
amount of formaldehyde if reared from seed in presence of the vapour. 
The question has not been further investigated. 
Theoretical Deductions from Results. 
The basis for further inquiry was the observation that formaldehyde 
may function, to a limited extent, as a source of food-material for plants in 
light, but not in darkness. This shows that the plant is possessed of some 
agency by means of which it is able to absorb formaldehyde. More than 
this cannot be assumed, for there are several explanations of the way in 
which formaldehyde might be used by the plant after its absorption. These 
may be expressed under two main headings : either formaldehyde is the 
first step in photosynthesis, and its further elaboration requires light energy ; 
or it is the last step in respiration, and is only used by the plant for photo- 
synthesis after being converted by the respiratory processes into carbon 
dioxide. In either case there is a further possibility that the agency in 
question, which may be an enzyme, does not attack formaldehyde 
specifically, but is a general reagent for the aldehydic grouping, used to 
polymerize or oxidize quite a different compound in the plant tissues. 
This last question led to a few experiments on acetic aldehyde, to see 
whether the aldehyde group would again be attacked. 
Effect of Traces of Acetic Aldehyde in the Air. 
Amount introduced into the Air-current. 
It was almost impossible to estimate this accurately, especially in 
water solution, because of the extreme volatility of the aldehyde, which 
caused the concentration to change continually. The method used was the 
same as for formaldehyde (see p. 419). 
Values. 
Source of Aldehyde. 
Properties of Air. 
Vol. Press. Temp. 
Wt. of ch 3 ch 2 o 
evolved. 
% CH 3 CHf) by 
pressure in air. 
litres. 
nun. 
grins. 
Pure aldehyde in bubbler. 
2-36 
773 1 3 ° 
3-8435 
52-1 
1*18 
773 12 0 
i-88oo 
5 1 '3 
40 % water solution of 
472 
772 T 5 * 5 ° 
o- 7 i 59 
4-9 
aldehyde 
472 
773 i 5 ° 
0-2584 
i-8 
Besides the uncertainty of these values the potash solution destroys 
a large proportion of the aldehyde vapour, forming a bright orange solution. 
However, the results serve to show that a large proportion of aldehyde 
could be obtained in the air. Probably the diffusion-bulb method, with 
pure aldehyde in the bulb, would be the best method of introducing it, but 
this was not used in the experiments. 
