198 PROCEEDINGS OF THE ACADEMY OF [1897. 



sary to be reproduced here, that this theoretical conception of the 

 formation of stem by the mere coiling of leaf-blade is legitimate, and 

 we are left only to account for the formation of buds, which are 

 eventually to become branchlets. 



The origin of buds is readily accounted for by the operation of 

 rhythmic growth. Growth is not continuous, but progresses by a 

 system of successive waves. The node is at once the resting place 

 of the old wave and the departing point of the new. The axial bud 

 is really the termination of the old growth wave. In many cases 

 during the resting period, it starts rapidly on with the new growth- 

 wave, assuming its original position as the leading shoot, when what 

 might have been the leader from a lower portion of the system of 

 arrested nodes forming the bud, is pushed aside to become what is 

 known as an extra axillary branch. This conception I cannot 

 claim as the belief of " most botanists," as it is essentially my own, 

 supported by facts detailed in many papers, which it is not neces- 

 sary to reproduce here. 



Recalling the evidence directly showing that the " gland " must 

 be a branch arrested in development, and carrying in our minds the 

 theoretical conception of the origin of the stem and buds, we can 

 readily understand how an arrested branch has been enveloped by 

 a coiling leaf-blade or set of leaf-blades on the petioles until all that 

 is left is consolidated apex which we now call a gland, and how glands 

 of this character which appear higher up on the leaf stalks are still 

 modifications of the same character, the whole compound leaf itself 

 being of precisely the same character in its original structure as 

 what we come ultimately to know as stem and branches. 



In my paper above cited I introduced the bud system of the 

 Honey Locust, Gleditschia, in confirmation of the position assumed 

 in regard to Cassia. Here again it furnishes evidence of the sound- 

 ness of the conclusions reached in this paper. The leaves are 

 abruptly pinnate as in Cassia, but the apex of the common petiole 

 or rachis does not appear as a gland so much as it does an undevel- 

 oped bud. Occasionally, however, it does develop, and the leaf 

 then has a single developed pinnated leaflet instead of the usual 

 abruptly terminating pair. In other instances one of the opposite 

 pair is abortive, in which case the one developed assumes the role of 

 a terminal leader, pushing aside and making axillary to itself the 

 usual terminal bud or gland. This latter instance strongly sustains 

 my point that when a subordinate bud gets the opportunity to push 



