PRESIDENT S ADDRESS. 
595 
chlorophyll. There is a strong resemblance between chlorophyll and 
hcematin — the colouring matter of haemoglobin of blood cells — 
but in the case of hcematin the iron is in chemical combination 
with it. The iron in hcematin can be extracted and a derivative is 
obtained termed hoematoporphyrine, which shows a strong similarity 
to a derivative of chlorophyll called phylloporphyrine. Some in- 
teresting results have recently been obtained from experiments by 
Schunke and Marchlewski from solutions of these two substances. 
The ethereal solutions are both the same colour, and the spectrum 
of both is precisely the same, each showing nine absorption bands, 
all of the same width and depth. Now this similarity between 
hcematin and chlorophyll is very remarkable, for both substances 
are concerned with the interchange of gases in the metabolic 
changes carried on in proteids, and both are dependent in some 
way upon the presence of iron for giving effect to these actions, 
although in the one case the iron is in chemical combination, whilst 
in the other it is only in what might be termed an imbibed state. 
As a result of these experiments some clue will probably be found 
for an explanation as to the precise physiological action of this 
remarkable substance. 
On account of the fixed position of the plant as compared with 
that of the animal, it is entirely dependent for its food upon its 
immediate environment, whilst the animal has to go in search of 
its food and on this account is furnished with certain organs of 
locomotion. Now in the matter of food, the animal, and when 
I say animal, man is of course included, is entirely dependent 
upon the plant for its supply. At the same time that the plant is 
manufacturing material for its own sustenance, it is also providing 
the food that will eventually be consumed by the animal. The 
animal has no power of manufacturing itself any food material, and 
can oidy convert to its own use, by chemical and other aids, thp 
material that it obtains from the plant; and so it comes about 
that, marvellous as it may appear, every bit of food we eat, whether 
vegetable or animal, has been manufactured originally, directly or 
indirectly, in the chloroplasts of leaves. Many other substances 
are formed within plants which are not required as food, some of 
