PREFACE TO SECOND EDITION 



At the suggestion of teachers who have been using the 

 first edition, laboratory directions are added for the study 

 of three additional forms, viz.: Exoascus deformans, 

 Microsphcera Aim, and Ustilago Ze&. The author is 

 indebted to Dr. E. W. Olive for the preparation of these 

 directions, and for a careful re-reading of the entire text, 

 resulting in the correction of various typographical errors 

 and other inaccuracies. 



The directions under the caption, VII, The Path of 

 Water in the Plant (B-F, pp. 35-41), have been con- 

 siderably extended at the suggestion of Prof. Ernest 

 Shaw Reynolds, who generously consented to prepare the 

 manuscript for the study of stem structure. Grateful 

 acknowledgment is also made to Prof. James S. Compton 

 for suggesting and preparing the manuscript for the study 

 of bacteria (pp. 145-148). 



The author will welcome constructive criticisms from 

 those who are using the book. 



C. STUART GAGER. 



BROOKLYN BOTANIC GARDEN, 



