ON THE PRODUCTION OF 

 NEW CELL FORMATIONS IN PLANTS. 



BY 



William Randolph Taylor, B.S., M.S. 

 With Plates LXXI to LXXVIII 



CONTENTS 



Introduction 271 



Experiments and Observations on Castanea 274 



Material and Methods 274 



Normal Histolog>' 274 



New Tissue Formations in Phloem 276 



Summary 281 



Experiments and Observations on Herbaceous Plants 282 



Material and Methods 282 



Summary of Experiments 283 



Effects of Injections on the General Growth 286 



Discussion of the Graphs 288 



Effects of Injections on the Stem Histology 289 



Summary 293 



Conclusions 294 



Bibliography 294 



Description of Plates 295 



Introduction 



For five years, from 1911-1916, Dr. Caroline Rumbold studied the 

 Chestnut Blight Disease in the Botanical Laboratory of the University 

 of Pennsylvania, endeavoring especially to develop a method of com- 

 bating the disease by the injection of chemicals into the trees. While 

 examining microscopically the trunks of certain of these trees, she dis- 

 covered that the structure of the bark in certain places differed strikingly 

 from thei. normal. Further study convinced her that these abnormalities 

 were dtie to the action of the injected substances and were formed in 

 response to some unusual physiological stimulus furnished by them. 

 At the suggestion of Dr. John M. Macfarlane, she embodied these ob- 

 servations in a paper (3) presented at the meeting of the American 

 Philosophical Society held on March 3, 1916. The importance of this 

 contribution consisted of the demonstration of unsuspected tissue- 

 formative powers located in the soft-bast region. As Dr. Rumbold 



271 



