NEW CELL FORMATIONS IN PLANTS 273 



This notable contrast suggested that other tissues, if treated in the 

 right way, might respond and form highly interesting structures. Some- 

 thing of this sort is indicated in the production of certain galls, as shown 

 by Houard. The formation of wood from the pith has been reported 

 by Jaccard, Prilheux, and especially Maiile. Production of bundle- 

 cambia from non-vascular tissues is not unknown as a normal feature 

 of certain plants. 



The work of the writer on the general subject of tissue modifications 

 may be divided into two parts. The first was an examination of a 

 large amount of Casianea material injected by Dr. Rumbold, to check 

 up her findings in that species. The second was a series of original 

 experiments, planned to extend the observations to other plants. 



In pursuance of the second part of this program, apparatus was con- 

 structed for the injection of trees, and the first experiment (on California 

 Privet) was set up on April 18, 1916. Subsequently several species 

 of trees were used, including Populus carolinensis, Catalpa bignonioides, 

 Ailanthus glandulosa, and Paulownia tomentosa. These experiments did 

 not yield very satisfactory results, due in part at least to excessive dilution 

 of the substance injected. From the first the writer determined to con- 

 duct similar experiments on herbaceous plants, and the injection of 

 these was begun the first week in July, 1916. It was hoped that the 

 reactions of these would furnish the key to the very complex conditions 

 present in Castanea, and the results secured from Ricinus cut by the 

 end of September verified these conjectures. However, the number 

 of plants available during the early summer was not very large, so during 

 the winter of 1916 roots of Polygonum Sieboldii were started in the 

 greenhouses and the shoots used. This plant was further experimented 

 on outdoors the next spring (1917). Altogether, about a hundred in- 

 jections of various kinds have been made, and suitable controls main- 

 tained. 



Briefly expressed, the object of this study was to produce special 

 cellular growth of all tissues capable of it, to determine what these 

 were, and what the morphology of the products of this growth might 

 be. In extension of the work of Dr. Rumbold, it was determined to 

 do this as far as practicable by the injection of various chemicals in 

 solution. As may easily be understood, it was not possible to eliminate 

 entirely the factor of mechanical injury. The mere puncture of the 

 needle in the work on herbaceous plants caused a slight reaction and com- 

 pUcated the result to some extent. Details of the behavior of the tissues 

 are given in the descriptions of individual cases. 



