Posts by Λεωτυχίδας

My home is on an island where it is very warm. I fly among the tall trees and eat fruit and insects. See my beautiful feathers. The ladies like to wear them in their hats. The feathers of my wife are brown, but she has no long tail feathers.

There are five successive and mutually dependent steps in the process of photosynthesis, as follows:

• There must be a gas exchange between the plant tissue and the surrounding air, by means of which the carbon dioxide of the air may reach the protoplasm of the chlorophyll-containing cells.
• Radiant energy must be absorbed, normally that of sunlight, although photosynthesis can be brought about by the energy from certain forms of artificial light.
• Carbon dioxide and water must be decomposed by the energy thus absorbed, and the nascent gases thus produced combined into some synthetic organic compound, with a resultant storage of potential energy.
• This first organic synthate must be condensed into some carbohydrate suitable for translocation and storage as reserve food.
• The oxygen, which is a by-product from the decomposition of the water and carbon dioxide and the resultant synthetic process, must be returned to the air by a gas exchange.

Of the five steps in this process, the first two and the last are essentially purely physical phenomena, the chemical changes involved being those of the third and fourth steps. Hence, it is only these two parts of the process which need be taken into account in a consideration of the chemistry of photosynthesis.

Once past the entrance it is obvious that we are in one of the strangest of all factories, for none of the rooms are truly square or oblong and their irregularity as to outline would drive your average foreman into profanity. Yet they are certainly divided into distinct classes, at least as to size and as to what the rooms contain. Some are apparently filled with nothing but air and have direct connection through the stoma with the outdoors. These are called intercellular spaces. Others, and these are most important, are filled mostly with the green coloring matter that gives the leaf its color.

This substance is known as chlorophyll, its individual units as chloroplasts, or literally, chlorophyll bodies. Quite independently of these chlorophyll cells or rooms, or the intercellular spaces which correspond to halls, there are some large and many small tubes. These are the veins of the leaf and their finer branches and by their direct connection through the stem to the roots, serve as the ducts through which some of the raw materials are brought into the factory.

In many partly desert or dry regions this production of leaflike stems or branches is common, an excellent garden example being asparagus, which came originally from Europe and the feathery growth of which is all stem. In Tasmania a kind of yew tree produces no leaves, all the foliage being modified stem, which is true of many kinds of spurge in the West Indies, where an almost impenetrable scrub is largely made up of a shrub which is apparently covered with leaves, all actually part of the branches and stems.