STRUCTURE.] DEVELOPMENT OF STIPULES. 287 



depressed lines which are continued to the base, in juxta- 

 position with the nascent lamellse. And the lobes do not 

 begin to have bosses scattered over their periphery, before 

 these lines manifest themselves on the lobes. At the same 

 time that the lines extend on the lobes, the bosses grow and 

 become cylindrical tumours. Their apex lastly is equally 

 furnished with opaque lines, which indicate the formation of 

 leafy lamellae, which, like the large lobes, have a duplicate 

 nervation. 



Stipules of Dicotyledonous plants appear like parts of 

 the blade of a leaf ; but after a time, in consequence of their 

 own development as well as of that of the petiole, they become 

 distinct organs no longer having an immediate connection 

 with the lamina. At a certain stage of their development 

 they are larger than the leaf that gave them birth. 



When stipules are first produced on the axis, they re- 

 semble, as all nascent leaves do, small tumours continuous 

 with the leaf-like expansion. It would in many cases be 

 difficult to decide whether they are always produced as two 

 distinct bodies. I have generally seen them like two pro- 

 jections confluent at their base and embracing the axis. 

 Sometimes (in many Papilionacese for example) we see clearly 

 that they do not appear as a continuous rim, but as two 

 small isolated tumours, which after a time either grow toge- 

 ther at their base, or remain constantly disunited. 



The lamina of a stipule is developed in precisely the same 

 way as that of a leaf, except that instead of folding down 

 upon itself, it extends in every direction, either immediately 

 on the axis, enveloping it, or on the youngest parts to which 

 it serves as a protecting envelope. The petiole, which expands 

 principally in length, and which limits one of the sides of 

 each stipule, is a constant check on the equilateral expansiou 

 of the blade of this organ. When this obstacle does not 

 exist (as for example in Melianthus major and the Poly- 

 gonese), growth takes place equally in all directions, and it 

 then frequently happens that the points that touch grow 

 together. 



The formation of the stipules of Melianthus major has 

 been already described. The annular rim constituting the 



