File:The animals and man; an elementary textbook of zoology and human physiology (1911) (14804736873).jpg

Identifier: animansmanelemen00kell (find matches)
Title: The animans and man; an elementary textbook of zoology and human physiology
Year: 1911 (1910s)
Authors: Kellogg, Vernon L. (Vernon Lyman), 1867-1937 McCracken, Mary Isabel
Subjects: Zoology Physiology
Publisher: New York, H. Holt and company
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
asm—which is the basicsubstance of every living thing—life appeared. Whence itcame or how it came to be produced are great questions thatscience has yet no answer for and may never have. Thespeculations about it are various: such as that living germsreached the earth from other planets in meteorites or ascosmic dust, or that it originated spontaneously underthe peculiar chemical and physical conditions of the earthssurface in those ancient dim days of the first hardening andcooling. And there are even some biologists who think thatsuch spontaneous generation of life from non-living sub-stances may be going on today. But no one of them hasbeen able to prove this. All life from previous life isthe dictum of most naturalists of today. And this poses theproblem of the origin of the first life as one far beyondpresent scientific knowledge. If, however science knows nothing about the origin of lifein the early days of the earths history it does know something 275 276 THE ANIMALS AND MAN
Text Appearing After Image:
FOSSIL ANIMALS 277 about what kinds of living creatures, both plants and ani-mals lived in those and succeeding ages. It knows this byvirtue of the preservation of parts of some of these animalsand plants as fossils. Animal fossils are the actual remains of bones or shellsor other (usually hard) parts of the body preserved intact insoil or rock; or else, and more commonly, are parts of ani-mals which have been turned into stone by slow replacementof these parts by rock particles; or else, finally, are parts ofwhich stony casts have been made. Examples of these threekinds of fossil are (i) extinct insects preserved in amber,teeth of ancient sharks, tusks of mammoths, shells of variousmolluscs; (2) petrified bones, corals, crinoids shells, etc.;(3) casts of insect wings, etc. Huxley said that fossils are only animals and plants whichhave been dead rather longer than those which died yester-day. This rather longer may mean anywhere from afew thousand to several million years. Geologists

Note About Images