42 NEW THEORY OF THE ORIGIN OF THE EARTH. 



with garments of green, jind blossom into loveliness, and breathe 

 in perfume, under the caresses of warmth and moisture. The 

 germs of life, the germs of all forms of life on the earth, may 

 have been in it from its origin, or they may have come to it in 

 planetary dust from other systems. This theory would be un- 

 tenable but for the recent discovery that even the extremely low 

 temperature of liquid oxygen does not destroy life germs. But 

 for this discovery it would be taken for granted that such germs 

 would perish, in the low temperature of interstellar space, in 

 their tlight from far-off systems to our own. When the earth 

 had grown large enough, say about 100,000,000 years ago, to 

 hold within its sphere of influence the gases that are the raw 

 materials of air and moisture, and began to wrap around its 

 shoulders an atmospheric garment for retaining solar heat, life 

 germs began to develop, one form of life after another, vege- 

 table and animal life, each kind arising whenever and where- 

 ever the conditions were suitable to its birth and preservation. 

 According to this theory the origin of life on the earth was many 

 millions of years earlier than would have been possible accord- 

 ing to the nebular hypothesis of a gradually cooling mass of 

 fiery matter and gas. Forms of life arose, lived for long ages, 

 and were succeeded by other forms, as the result of climatic and 

 other changes. Some of them have left their bones in the coal 

 measures. The rocks testify of them. We have their skeletons, 

 and they tell us of the state of the earth when they lived upon it. 

 And finally, millions of years, perhaps, after the first animal 

 had basked in the sunlight of earthl}' life, and probably a 

 million or more years ago, man appeared. His origin is no 

 more mysterious than the origin of any other animal, no more 

 mysterious than the origin of any plant or vegetable. He is 

 only a grain of sand on the shores of the great ocean of life. He 

 arose at different times, on different continents, 

 of different degrees of intelligence and with different 

 habits, when the earth had become fit for his habitation. In 

 one country he was a cave-dweller, in another a mound-builder, in 

 another something else. In one place he lived on shellfish, in 

 another on fruit. In warm countries he Went naked, and in 



