The Presidential Address. 
83 
edition, as also in liis ‘Antiquity of Man,’ he not only gave a 
masterly exposition of the Darwinian theory, but added 
considerably to its weight, and enforced its acceptance by 
several new and striking lines of argument. 
It would lead me too far astray on this occasion were I to 
attempt to go in any detail over the various lines of evidence 
converging upon the central idea of evolution. It suffices to 
say that many large groups of biological facts that had before 
appeared isolated and inexplicable were not only in the 
strictest scientific sense explained, but “as by the'stroke of 
the enchanter’s wand” the various great subdivisions of 
Biology fell into, and became part of, Darwin’s scheme of 
Nature. “ Every ray is gathered into one focus, and the rich 
development of theory guides the apparently most remote 
phenomena of organic life into the stream of proof.” 25 Let 
us consider, for instance, the generalised facts of Embryology. 
The development of an organism from the first germ to the 
mature state is essentially a process of evolution. The 
researches of embryologists, beginning with the illustrious 
Karl Ernst von Baer, and ending alas! in recent times with 
the lamented Francis Maitland Balfour, have shown that in 
the course of its individual development an animal passes 
through stages which approximate it at first to the lowest 
types, and then in succession to types of increasing spe¬ 
cialisation. The individual in fact “rises in organisation ” 
in the same sense as does the species. Specialisation increases 
with development, till finally the adult animal acquires all 
the characters of the species to which it belongs. How are 
such facts intelligible if we reject the theory of descent? 
The researches of Darwin upon the laws of inheritance have 
shown that all characters tend to be transmitted by parents 
to their offspring at the same age or a little earlier than they 
appear in the parents. This is Haeckel’s law of “homo¬ 
chronic heredity.” The embryonic phases of an organism 
are thus reminiscences of its past development—recapitula¬ 
tions of the stages through which its ancestors passed in the 
course of their evolution. The individual development or 
25 Lange, l. c., vol. iii., p. 31, 
