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finally discuss the bearing of that conclusion upon the hypo- 
theses which have been entertained respecting the Origin of 
Man. 
The facts to which I would first direct the reader’s atten- 
tion, though ignored by many of the professed instructors 
of the public mind, are easy of demonstration and are univer- 
sally agreed to by men of science; while their significance is 
so great, that whoso has duly pondered over them will, I 
think, find little to startle him in the other revelations of 
Biology. I refer to those facts which have been made known 
by the study of Development. 
It is a truth of very wide, if not of universal, application, 
that every living creature commences its existence under a 
form different from, and simpler than, that which it eventually 
attains. 
The oak is a more complex thing than the little rudi- 
mentary plant contained in the acorn; the caterpillar is 
more complex than the egg; the butterfly than the cater- 
pillar; and each of these beings, in passing from its rudi- 
mentary to its perfect condition, runs through a series of 
changes, the sum of which is called its Development. In 
the higher animals these changes are extremely complicated ; 
but, within the last half century, the labours of such men as 
Von Baer, Rathke, Reichert, Bischof, and Remak, have almost 
completely unravelled them, so that the successive stages of 
development which are exhibited by a Dog, for example, are 
now as well known to the embryologist as are the steps of 
the metamorphosis of the silk-worm moth to the school-boy. 
It will be useful to consider with attention the nature and 
the order of the stages of canine development, as an ex- 
ample of the process in the higher animals generally. 
The Dog, like all animals, save the very lowest (and further 
inquiries may not improbably remove the apparent exception), 
commences its existence as an egg: as a body which is, in 
every sense, as much an egg as that of a hen, but is devoid of 
