d be required by the formation of formaldehyde and hydrogen peroxide
from carbonic acid.

More recently, Ewart has showed that formaldehyde can combine chemically
with chlorophyll; from which fact, Schryver deduces the theory that if for
any reason the condensation of formaldehyde into carbohydrates by the cell
protoplasm does not proceed as rapidly as the formaldehyde is produced by
photosynthesis, the excess of the latter enters into combination with the
chlorophyll, and that if condensation into sugar uses up all the free
formaldehyde which is present in the active protoplasm, the compound of
formaldehyde with chlorophyll is broken down setting free an additional
supply for further sugar manufacture. According to this conception there
are, in the chlorophyll-bearing protoplasm, not only the agencies for the
production of formaldehyde from carbon dioxide and water and for the
condensation of this into carbohydrates, but also a chemical mechanism by
means of which the amount of free formaldehyde in the reacting mass may be
regulated so that at no time will it reach the concentration which would be
injurious to the cell protoplasm or fall below the proper proportions for
sugar-formation. This explanation affords a satisfactory solution of the
difficulty which formerly confronted the students of photosynthesis,
namely, the fact that free formaldehyde is powerfully toxic to cell
protoplasm. Without some such conception, it was difficult to imagine how
the presence of formaldehyde in the cell contents, even as a transitory
intermediate product, could be otherwise than injurious.

As a result of these studies, the nature of the chemical changes which
result in the production of formaldehyde as the first product of
photosynthesis, with the liberation of a volume of oxygen equal to that of
the carbon dioxide consumed, seems to be fairly well established.

THE PRODUCTION OF SUGARS AND STARCHES

The next step in the process, the conversion of formaldehyde into sugars
and starches, is not necessarily a _photo_synthetic one, as it can be
brought about by protoplasm which contains no chlorophyll or other
energy-absorbing pigment. It is, however, a characteristic synthetic
activity of living protoplasm. There is little definite knowledge as to how
the cell protoplasm accomplishes this important task. As has been pointed
out, the polymerization of formaldehyde into a sugar-like hexose, known as
"acrose," can b