viii PREFACE 



It is easier to examine live plants in a laboratory than live 

 animals. They are easier to rear. They reproduce as a rule 

 more quickly and more continuously and they require much 

 less attention. Further, all the older Universities of Europe 

 and many of our Schools have Botanical Gardens, but I have 

 never come across a University or a School which has an 

 adequate Zoological Garden. 



The only really difficult part of this book is that deahng with 

 the alternation of generations in plants. But it is such a 

 wonderful illustration of evolution and its whole story is so 

 romantic that I have ventured to give a short sketch of its 

 progress from the simplest seaweeds to the highest flowering 

 plants, a sketch far too condensed. Here at least the student 

 may require the aid and explanations of a teacher. 



Finally I venture to hope that this book will be not without 

 intere&t to the public that is not preparing for examinations, 

 and thank heaven that public is still in the great majority! 



A E. SHIPLEY. 



Christ's College Lodge, Cambridge, 



17 th November y 1923. 



PREFACE TO THE SECOND EDITION 



There are comparatively few alterations in this new edition 

 of "Life." A few crooked paths have been straightened out, 

 but the most important alteration is the re-writing of page 36. 

 In the first edition the account of the connexion between 

 clilorophyll and haemoglobin was not accurate. 



I have also incorporated a more modern view of the 

 function of the contractile vacuole. 



For many of the corrections I am indebted to my friends 

 Mr J. Barcroft, F.R.S. of King's College and Mr C. F. A. 

 Pantin of the Marine Biological Laboratory, Plymouth. 



A. E. S. 

 Christ's College Lodge. 

 4//< February, 1925. 



