84 BOTANICAL GAZETTE [FEBRUARY 
the same relation as does fuel to the engine, and that what happens 
is an actual oxidation of the food immediately and directly; in fact, 
a process precisely parallel to the burning of the same food outside 
the body. 
One evident outcome of that idea is the current classification of 
foods into plastic and dynamogenous—those which are useful in 
building up the body, and those that are useful in producing heat 
within the body; into “‘fattening foods” and “heat-producing” 
foods. You are doubtless familiar with these phrases. 
But if foods are “burned” in the body, it must be important to 
know how much oxygen enters it, and how much carbon dioxid 
and water leave it, so as to discern the ratio which exists between 
them. Plainly a basis for this must be a comparison of the differ- 
ences between the combustion of foods outside the body and their 
“combustion” within the body. Yet, strangely, this has not been 
made until recently. Without giving the full tables, let me show 
the results arrived at by two observers, regarding two of the most 
common plant foods, glucose and tartaric acid. These observers 
assume, you will notice, that the processes are comparable. The 
‘ co 
results are stated as ratios of 
oO, y 
By RESPIRATION 
By Com- 
Foop BUSTIO’ 
Diakonow Purjewicz 
Glucose - - - - - - - aoe 93 
100 100 10° 
Tartaricadd - - - - 160 = 162 
100 100 100 
_ Dtakonow’s whole series shows that in combustion the carbon 
dioxid was always less than in respiration; Puryewicz found (with 
the exception of tartaric acid, and even there the difference between 
his results and Drakonow’s is in the same direction) that it was © 
always gi greater, his results being absolutely different in significance 
oo. frome DraKonow’ s. And this is a good type of the results to be 
ae — in Uecescreans the literature! I am not now concerned in 
mining which set of results is correct, inasmuch as I believe 
