THE KINSHIP OF LIFE. 37 
that which is injurious. The process of development 
of any individual is that of its ancestors with the harm- 
ful stages abbreviated or suppressed. The young frog 
has the ancestral gill of the fish and so has the human 
child in embryo. This stage is useful to the frog; it is 
not harmful to the unborn child. It is thus retained by 
heredity, but its retention is always governed by its pos- 
sible harmfulness. 
It is not an easy task to put in a few words and popu- 
lar language even a hint of the wealth of evidence which 
embryology brings to the support of the 
theory of evolution. This evidence was 
in Mr. Darwin’s mind the most convinc- 
ing of all evidence, its force being even stronger than 
that derived from his own studies in geographical and 
geological distribution. In this connection the follow- 
ing paragraphs have been contributed by Dr. John Ster- 
ling Kingsley: 
“To appreciate the weight and extent of embryo- 
logical evidence, one needs the special training of the 
biological laboratory, for it is only by watching the won- 
derful changes which every egg goes through in its de- 
velopment that one can begin to realize the importance 
of the facts. The training of the metaphysician is here 
of no value, for it is not of the slightest avail in weigh- 
ing the evidence. 
“To state this evidence briefly, we may state that the 
history of every developing egg and embryo is utterly 
incapable of explanation from any other standpoint 
than that of evolution. Why should the young verte- 
brate have kidneys like those of worms? Why does 
man have muscles to move the ears? Why do young 
spiders develop legs which will utterly disappear in the 
adult? Why does the nervous system communicate 
with the alimentary canal in the young frog or bird? 
Embryology and 
evolution. 
