COMPAKATIVE ANATOMY OF THE CUCUllßlTACE.E. 



CHAPTER I. 



THE STEM. 



Coiitoni'. In tlio Caeurbitacejt} the contour of a transverse 

 section througli the stem differs considerably in different species and 

 varies even in one and the same individual according to its age. 

 When young the outline of the stem is pentagonal, but becomes 

 more or less roundish as the stems grows older. The stems of 

 Benincasa cerlfera and Lagenarla vulgaris are especially remark- 

 able for a secondarily produced process in the furrows. Generally 

 speaking, young stems are solid, but in advanced age some stems 

 acquire a wide lumen in the centre, and the formation of a 

 narrow compressed cavity is common in the very old stems of 

 many species. In Benincasa cerlfem (PI. I. fig. 1-4), Lagenaria 

 vulgaris, and Cucurbita Pepo, when the stems are still young, a 

 remarkable roundish hollow is already formed in the centre by 

 a gradual splitting of the central tissue. 



The full-grown stems of Luffa cylimlrica and L. acutangula 

 as well as the old stems of 3Iomordica charantia and Actinosiemma 

 racemosum have sharply ridged angles. ]\Iicroscopical examination 

 shows that the ridges of Luffa cylindrica (PL II. Fig. 35) and 

 L. acutangula consist only of outgrowths of the collenchyma, 

 while those of Momordica charantia (PI. II. Fig. 36) and 

 Actinostemma racemosum, in spite of their resemblance to the 

 former in external appearance, are formed Ijy newly developed 

 secondary tibro- vascular bundles, which have originated from the 



