i 9 isl PETRY—OPHICGLOSSACEAE 359 



two growing points were doubtless established. This produced a 

 physiological demand which, operating under the conditioning 

 factors just described, produced two branch steles. 



The conclusion that is reached, therefore, is that the vascular 

 connections of the branches are determined in general by three 

 factors. These factors are (1) the presence of stelar tissues capable 

 of growth within the range of the influence of the developing 

 branch; (2) the nature of the growth which can be induced in those 

 tissues, in particular, whether such growth is cambial or not; 

 (3) the physiological demand produced by the growing branch. 

 The first of these factors will vary with the distance of the bud from 

 the leaf trace as compared with its distance from the stem stele; 

 and, more particularly, with the age of those structures when the 

 branch begins to develop. The second factor may be considered 

 to be relatively constant for any one species but to vary widely 

 with different species. The vascular connection produced is the 

 direct result of the third factor acting upon and limited by the 

 other two; the individual conditions give to this third factor a 

 special value for each particular case; the resultant structures are 

 therefore direct responses to unknown and varying conditions and 

 of physiological interest only. It is therefore concluded that the 

 vascular connections of the branches of Botrychium have little or 

 no phylogenetic significance. 



THE ORIGIN AND DEVELOPMENT OF THE AXILLARY BLTDS 



In view of the foregoing conclusion, attention has been turned 

 from the anatomy of the branch connections to the examination of 

 the origin of the axillary buds. Since Lang's description of these 

 buds in B. Lunaria deals only with the mature structures, the further 

 investigation has been directed toward the examination of the 

 origin and development of these buds in B. obliqmim. 



The apical region. — The apical region of Botrychium has been 

 described in detail by Holle (6), Campbell (3), and Bruchmann 

 (2). All agree that growth takes place by means of an apical cell 

 of the form of a triangular pyramid, and that each segment of the 

 apical cell probably gives rise to a leaf. Bruchmann states that 

 in B. Lunaria leaf formation begins by the appearance of an apical 



