president's address — SECTION D. 109 



in particular instances — that, for example, all geese are, like other 

 birds, hatched from eggs ; all marsupials, like other mammals, born 

 from the womb. 



But constancy of parentage is not to all minds a sufficient expla- 

 nation of the origin of life in the individual. It is pos-ible for a 

 living body to derive its substance from its progenitors, its life 

 from some extraneous source. If this were more than a gratuitous 

 hypothesis, if it were supported by any evidence whatever, one of 

 the further questions which biology has yet to solve would tend 

 towards solution. Not only should we then have some reason to 

 think that life is not simply the quality of living matter, but an 

 entity capable of existing apart from it — a view which has been 

 gradually shut out by every increment of knowledge ; but we 

 should be inclined, in proportion to the proof offered, to believe 

 that even under present terrestrial conditions a substance capable 

 of life can exist apart from that which alone proves its capacity for 

 life — a rather profound problem, and one not to be solved by 

 offhand inconsiderateness. But the evidence is wanting and the 

 assumption is improbable in itself. There are three possible modes 

 by which the incipient organism may receive life, and of these we, 

 as reasoning men, must choose the most reasonable, remembering 

 the while that it is life simply, the common attribute of plant and 

 animal, that has to be considered, and disallowing all exclusive 

 thought of ourselves and our human gifts. Either the offgoing 

 part of the parent is dead, an effete excretion, and lite is introduced 

 to it from without, or it is a living part from which in the process 

 of separation inherent life is expelled in order to be replaced by 

 life from without, or the life of the offspring as a separate body is 

 in uninterrupted continuity with that of its parent substance. 

 Remembering again that nature works in the ways that are most 

 direct, and that she secures economy of labor by never doing any- 

 thing, on the large scale at least, unnecessarily, we shall have no 

 difficulty in fixing the respective values of these alternatives and 

 assigning the highest to that which affirms continuity between the 

 two terms of life, the old and the new. But biology does not leave 

 us to judge by mere likelihood. She declares that her peculiar 

 instrument, the microscope, has revealed to her as a fact that the 

 initial point of life is not otdy of itself a living being Avhile still 

 an intrinsic part of the parent body, but that alter separation it 

 necessarily carries forward the parental life. She is shown a living- 

 body gradually constricted in the middle till it parts asunder, and 

 each half goes its living way, a part of the body wall bulging out- 

 wards, and assuming more and more the form of a body similar to 

 that from which it sprung till it either drops off more or less fully 

 accoutred for independence or grows up to maturity without losing^ 

 its connection with the parent mass. In these cases continuity of 

 life, if not in the latter case continuity of the entire sub.stance. is 

 beyond question. Between these instances of life — at once extended 



