Another method of retracing the lost early chapters in the
development of life is furnished by embryology. The value of this
method is not recognised by all embryologists, but there are now
few authorities who question the substantial correctness of it,
and we shall, as we proceed, see some remarkable applications of
it. In brief, it is generally admitted that an animal or plant is
apt to reproduce, during its embryonic development, some of the
stages of its ancestry in past time. This does not mean that a
higher animal, whose ancestors were at one time worms, at another
time fishes, and at a later time reptiles, will successively take
the form of a little worm, a little fish, and a little reptile.
The embryonic life itself has been subject to evolution, and this
reproduction of ancestral forms has been proportionately
disturbed. Still, we shall find that animals will tend, in their
embryonic development, to reproduce various structural features
which can only be understood as reminiscences of ancestral
organs. In the lower animals the reproduction is much less
disturbed than in the higher, but even in the case of man this
law is most strikingly verified.
Pages:
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128