Page:Popular Science Monthly Volume 2.djvu/98

86 must refer the reader to Dr. Bastian's work, where the history of recent investigations upon the subject is given in detail.

The growth of new distinctions and more precise ideas in science requires the use of new terms to mark them, while, at the same time, old terms have to be discarded, as conveying erroneous ideas. The term "spontaneous generation," although so long applied to the subject, that it will be apt to continue in popular use, has lost its place in biological science, as it is too indefinite, and conveys a false idea. Those who hold that life originates directly from non-living matter do not consider that its production in this way is any more truly "spontaneous" than its usual production from parental germs. Several words have been introduced by different writers to define their ideas, which it is desirable here to explain.

Biogenesis is the term applied by Prof. Huxley to the derivation of life from previously-existing life; and Abiogenesis to the production of life from non-living matter. The latter term, therefore, corresponds to what is commonly meant by "spontaneous generation."

Homogenesis, or Homogeny, are terms that have been long applied to the production of like from like; that is, the common case in which the living parent gives rise to offspring which pass through the same changes as itself.

Heterogenesis, or Heterogeny, is the name applied to processes by which living things arise from the matter of preexisting organisms, belonging to a totally different species. It has, however, had different meanings, and its use has created some obscurity, but it is customary to apply it to the so-called cases of "spontaneous generation;" and those who hold this doctrine are therefore known as Heterogenists.

Panspermy is the name given to the doctrine of diffused atmospheric germs, as the sources of infusorial life, and those who hold to this view are called Panspermists. "Spontaneous generation," so called, or the production of living creatures without parentage, may take place in two ways: either from preexisting living matter (heterogenesis), or from not-living matter. This production of living forms from inorganic materials is termed by Dr. Bastian Archebiosis, which literally means "beginning to live."

It was in the course of some investigations upon the microscopical characters of the blood of persons suffering from acute diseases that Dr. Bastian's attention was first drawn to the question of the origin of life. He soon became interested in it as an independent scientific problem, and pursued the inquiry experimentally for three years, the results being recorded in the present work. In Part I. he aims to show that the now commonly-accepted doctrine of the Correlation of Forces favors the independent origin of living matter. In this part, also, he has an elaborate chapter showing that the cell cannot be regarded as the ultimate organic unit. In Part II., under the head of Archebiosis, he takes up the real issue of the spontaneous generation