14 ELEMENTS OF PLANT BIOLOGY 



majority are copied, with or without modification, from 

 published figures. They are intentionally limited in 

 number, no attempt having been made to illustrate 

 everything that is described when the details of 

 structure can quite easily be made out on the objects 

 seen in the laboratory. Accurate pictures of the 

 material actually studied provide too great a tempta- 

 tion to copy the picture rather than the object, and 

 it is, of course, impossible to lay too great stress 

 on the value of making careful drawings from the 

 objects themselves. For this reason a good deal of 

 the structure of the higher plants is illustrated by 

 diagrams and generalised pictures which are not 

 faithful copies of nature. 



Professor A. E. Boycott, of University College, 

 London, has been good enough to read the chapter 

 on Bacteria, and has given me the help of his very 

 valuable criticisms. My colleague, Mr. F. T. Brooks, 

 has kindly performed a similar service in reading 

 Chapters X and XI, on the Fungi. Mr. S. M. 

 Wadham, the Senior Demonstrator in Botany at 

 Cambridge, has given ungrudging help in organising 

 the Practical Work and suggesting improvements. 

 Finally, I am deeply indebted to my friend Dr. F. F. 

 Blackman, who has placed at my disposal his critical 

 knowledge of plant physiology and biochemistry by 

 advising in detail on Chapters II, III and VII, as well 

 as on other smaller sections of the book. 



A. G. T. 



CAMBRIDGE, 

 July, 1922. 



