2G COHESION 



of the cohesion of the jnargins at the base and apex 

 of the leaf, which thus appears pei'forated. This ap- 

 pearance, however, is probably due to some other 

 cause. When tlie leaves are verticillate and numerous, 

 and they become coherent by their margins, they form 

 a foliaceous tube around the stem. When there 

 are but two opposite leaves, and these become united 

 by their margins, we have a state of things precisely 

 resembling that to which the term connate is applied. 



Fusion of the edges of the cotyledons also occasion- 

 ally takes place, as in Ehenus cretica} It has also 

 been observed in Titlioma, and is of constant occm*- 

 rence in the seed leaves of some Meseiahryanthenia. 

 This condition must be carefully distinguished from 

 the very similar appearance produced by quite a dif- 

 ferent cause, viz., the splitting of one cotyledon into 

 two, which gives rise to the appearance as if two were 

 partially united together. 



Some of the ascidia or pitcher-like formations are 

 due to the cohesion of the. margins of two leaves, as in 

 a specimen of Urassulu arbor escens, observed by C. 

 Morren. 



Fio. iW. Two-leaved pitcher of Craasvla arborescens, after C. Morren. 



The stipules may also be fused together in different 



' De Candolle, ' Mem. Leg.,' pi. v, fig. 14; 



