A Short History of the World

s, it was supposed that the different species of plants and animals were fixed and f

se of ages, and this again expanded into a belief in what is called Organic Evolution, a belief that all species of life upon earth, animal and vegetable alike, are desce

ble with sound Christian, Jewish and Moslem doctrine. That time has passed, and the men of the most orthodox Catholic, Protestant, Jewish and Mohammedan belief are now free to accept this newer and broader view of a common origin of all living thi

assimilate other matter into themselves and make it part of themselves, and they can reproduce themselves. They eat and they breed. They can give rise to other individuals, for the most part like themselves, but always also a little different from

THYS MILLERI OR SEA SCO

vidual differences make them better adapted to the new conditions under which the species has to live, and a number whose individuals whose individual differences make it rather harder for them to live. And on the whole the former sort will live longer, bear more offspring, and reproduce themselves more abundantly than the latter, and so generation by generation the average of the species will change in the favourable direction. This process, which is called

ly no definite knowledge and no convincing guess yet of the way in which life began. But nearly all authorities are agreed that it probably beg

CLADOSELACHE,

Hist.

d sun. Early conditions favoured the development of every tendency to root and hold on, every tendency to form an outer skin and casing to protect the stranded individual from immediate desiccation. From the very earliest any tendency to sensitivene

ere protections against drying rather than against active en

ocks called the Silurian division, which many geologists now suppose to be as old as five hundred million years, there appears a new type of being, equipped with e

NOIDS OF THE

ice W

attern now gone from the earth, and fishes allied to the sharks and sturgeons of to-day, rushed through the waters, leapt in the air, browsed among the seaweeds, pursued and preyed upon one another, and gave a new l

living relations, and from other sources. Apparently the ancestors of the vertebrata were soft-bodied and perhaps quite small swimming creatures who began first to develop hard parts as teeth round and about their mouths. The teeth of a skate or dogfish cover the roof and floor of