Tendrils of Cucurbitacece. 243 



of the family, there would at least be but few and unimpor- 

 tant structural differences as observed in the various genera. 

 No exact comparison having been instituted, however, it has 

 been impossible to give definite expression to any settled 

 view on this point, up to the present time. Our recent 

 observations, however, enable us to supply this deficiency. 

 As we have already detailed the structure of the tendril in 

 Cucurbita, it may be well to institute our comparisons with 

 it, more especially as we are to demonstrate how far it may 

 be considered the type, and reference should be made to 

 our description for comparison. 1 



All the tendrils of the family, so far as observed, present 

 the same general features of internal structure, at least so 

 far as the more important mechanical elements are 

 concerned, e.g., the distribution of the tissues, particu" 

 larly with reference to the strong localization of bast and 

 the development of vibrogen bands. Externally, the 

 form varies somewhat, though in most cases in no essential 

 particular. All are more or less well rounded at the base 

 and flattened toward the tip, usually before the middle 

 section is reached, but, with one or two exceptions, the 

 lower or sensitive surface is rounded. In Sicyos, an excep- 

 tion appears in the strong flattening of both sides for some 

 distance back from the tip. Citrullus and Lagenaria are 

 flattened only on the upper side, but show no channel, or 

 mere rudiments of one, while Cucumis is not only channelled 

 above, but shows several longitudinal furrows in other parts 

 of the circumference. Citrullus, Lagenaria, Luffa, Benin- 

 casa and Cucumis are more or less hairy all over the base; 

 Ehynchocarpa is hairy throughout, while Sicyos is equally 

 smooth throughout its entire length. It is a noticeable 

 fact, however, that in nearly all the genera the hairs disap- 

 pear at a short distance from the base, over the entire region 

 of the collenchyma tissue of the lower side, and even in 

 Rhynchocarpa, where the hirsuteness is so strongly defined 

 there are comparatively few hairs in this region. The 

 same is true of the two collenchyma regions lying laterally 



1 Trans. R. Soc. Can., IV. 



