The most minute of these are known as microbes. They are chiefly composed of a single cell, in the midst of which is the protoplasm, or material in which life resides, but the exact nature of which is still a mystery.
A FUNGUS (Cordyceps Andrewsii) GROWING FROM THE HEAD OF A CATERPILLAR.
A FUNGUS (Cordyceps Andrewsii) GROWING FROM THE HEAD OF A CATERPILLAR.
One of the most useful and fascinating studies in modern times is Geographical Botany. It is found to have a close relation to the history of man, and to the changes which have occurred on the surface of the earth. Plants follow man wherever he wanders; and though every other trace of man should be abolished on the American continent, the plants that came with him from the Old World would enable the future historian to follow his tracks here pretty well. No one has any historical evidence that what is now the Pacific Ocean was once land, and that the area between the Pacific Ocean and the Mississippi was once a huge sea, but botany tells the plain story. Only for botany we should not know that the land now serving as the poles was once within the tropics; and mainly by fossil gum trees on the American continent, and the existence still of a few plants common to Australia, have we the knowledge of some land connection between these distant shores. Island floras, some of the species of which are now found only in very limited areas, tell of large tracts submerged of which only the mountain peaks are left as small islands, lonely in a wide expanse of water, while other islands, with only a limited number of well known species, tell of new upheavals within modern times.
It is in these lines chiefly that botany has advanced during the century. Herbariums for dry and botanic gardens for living plants are essential. The latter are not as necessary to the study as formerly, as the facilities for travel bring the votaries of the science to distant places in a short time. Nature furnishes the living material for study at a less outlay of time and money than in the old way of growing the plants for the purpose. Few modern botanic gardens have the fame of those of the past. It is the great Herbarium of Kew, rather than the living plants, that makes that famous spot the great school for botany to-day. In our own country, the Herbariums of Cambridge, Mass.; Columbia College, New York; the National at Washington; and that of the Academy of Natural Sciences of Philadelphia, are the most famous in America.