The task of the biologist is a double one. His more immediate effort is to inquire into the nature of the existing organism, to ascertain in what measure the complex phenomena of life as they now appear are capable of resolution into simpler factors or components, and to determine as far as he can what is the relation of these factors to other natural phenomena. It is often practically convenient to consider the organism as presenting two different aspects--a structural or morphological one, and a functional or physiological--and biologists often call themselves accordingly morphologists or physiologists. Morphological investigation has in the past largely followed the method of observation and comparison, physiological investigation that of experiment; but it is one of the best signs of progress that in recent years the fact has come clearly into view that morphology and physiology are really inseparable, and in consequence the distinctions between them, in respect both to subject matter and to method, have largely disappeared in a greater community of aim. Morphology and physiology alike were profoundly transformed by the introduction into biological studies of the genetic or historical point of view by Darwin, who did more than any other to establish the fact, suspected by many earlier naturalists, that existing vital phenomena are the outcome of a definite process of evolution; and it was he who first fully brought home to us how defective and one-sided is our view of the organism so long as we do not consider it as a product of the past. It is the second and perhaps greater task of the biologist to study the organism from the historical point of view, considering it as the product of a continuous process of evolution that has been in operation since life began. In its widest scope this genetic inquiry involves not only the evolution of higher forms from lower ones, but also the still larger question of the primordial relation of living things to the non-living world. Here is involved the possibility so strikingly expressed many years ago by Tyndall in that eloquent passage in the Belfast address, where he declared himself driven by an intellectual necessity to cross the boundary line of the experimental evidence and to discern in non-living matter, as he said, the promise and potency of every form and quality of terrestrial life. This intellectual necessity was created by a conviction of the continuity and consistency of natural phenomena, which is almost inseparable from the scientific attitude towards nature. But Tyndall's words stood after all for a confession of faith, not for a statement of fact; and they soared far above the _terra firma_ of the actual evidence. At the present day we too may find ourselves logically driven to the view that living things first arose as a product of non-living matter. We must fully recognize the extraordinary progress that has been made by the chemist in the