10 © PRESIDENT’S ADDRESS. 
determination of sex is accomplished in some of the forms of life— 
though, I hasten to add, we have no inkling as to any method by which 
that determination may be influenced or directed. It is obvious that 
such discoveries have bearings on most of the problems, whether 
theoretical or practical, in which animals and plants are concerned. 
Permanence or change of type, perfection of type, purity or mixture 
of race, ‘ racial development,’ the succession of forms, from being vague 
phrases expressing matters of degree, are now seen to be capable of 
acquiring physiological meanings, already to some extent assigned with 
precision. For the naturalist—and it is to him that I am especially 
addressing myself to-day—these things are chiefly significant as relating 
to the history of organic beings—the theory of Evolution, to use our 
modern name. They have, as I shall endeavour to show in my second 
address to be given in Sydney, an immediate reference to the conduct 
of human society. 
I suppose that everyone is familiar in outline with the theory of 
the Origin of Species which Darwin promulgated. Through the last 
fifty years this theme of the Natural Selection of favoured races has been 
developed and expounded in writings innumerable. Favoured races 
certainly can replace others. The argument is sound, but we are doubt- 
ful of its value. For us that debate stands adjourned. We go to 
Darwin for his incomparable collection of facts. We would fain 
emulate his scholarship, his width and his power of exposition, but 
to us he speaks no more with philosophical authority. We read his 
scheme of Evolution as we would that of Lucretius or of Lamarck, 
delighting in their simplicity and their courage. The practical and 
experimental study of Variation and Heredity has not merely opened 
a new field; it has given a new point of view and new standards of 
criticism. Naturalists may still be found expounding teleological 
systems’ which would have delighted Dr. Pangloss himself, but at 
the present time few are misled. The student of genetics knows that 
° TI take the following from the Abstract of a recent Croonian Lecture 
‘On the Origin of Mammals’ delivered to the Royal Society :—‘In 
Upper Triassic times the larger Cynodonts preyed upon the large 
Anomodont, Kannemeyeria, and carried on their existence so long as these 
Anomodonts survived, but died out with them about the end of the Trias or 
in Rhetic times. The small Cynodonts, having neither small Anomodonts nor 
small Cotylosaurs to feed on, were forced to hunt the very active long-limbed 
Thecodonts. The greatly increased activity brought about that series of 
changes which formed the mammals—the flexible skin with hair, the four- 
chambered heart and warm blood, the loose jaw with teeth for mastication, 
an increased development of tactile sensation and a great increase of cerebrum. 
Not improbably the attacks of the newly evolved Cynodont or mammalian type 
brought about a corresponding evolution in the Pseudosuchian Thecodonts, which 
ultimately resulted in the formation of Dinosaurs and Birds.’ Broom, R., 
Proc. Roy. Soc. B., 87, p. 88. 
