COMPARATIVE ANATOMY OF THE CUCURB1TACEJ<:. 27 



speaking, a transverse section cut through the distal portion shows 

 a deep groove on the upper surface, while that of the proximal 

 portion appears roundish, the groove becoming extremely shallow. 

 The middle portion has an intermediate character. Besides, 

 though many of the petioles are solid some of them have a large 

 central hollow throughout, this being the case in Benincasa 

 cerifera, Cucurbita Fepo (PL I. Fig. 15-17), and Lujfa 

 acutangula. 



Stoinafa. Stomata are not found on the epidermis, where 

 the collenchyma is developed ; they are present only in the 

 intercollenchymatous portions. The following are the average 

 nund^ers of the stomata on the petioles of eacli species : 



