COMPARATIVE ANATOMY OF THE CUCURBITACE^. 9 



The old stems of some species have only one group of 

 sclerenchymatous cells outside of each fibro- vascular bundle, as 

 in Aciinoslemrna racemosuin, MelotJwia japonica, Schizopepon 

 hryoniarfolius, var. japo7iicus, Citrullus vulgaris, Lagenaria vulgaris, 

 Tricliosanthes cucumeroides, T. japonica, T. multiloba, and Gym- 

 nostemma cissoides; some have two sclerenchyma masses tangentially 

 arranged, which have been formed by a rupture of the original 

 continuous ring, as in 3Iomordica Oharaniia, Luffa cylindrica, 

 L. acidangula, Cktcumis sativus, C. Melo, Benincasa cerifera, and 

 Gucurhita Pej)o. There is a remarkable development of secondary 

 sclerenchyma in the very old stems of Actinostemma racemosum, 

 3Ielothria japonica, Momordica Charantla, Luffa cylindrica, L. 

 acutangula, Citrullus vulgaris, Tricliosanthes cucumeroides, T. 

 japonica, T. multiloba, and Gymnostemma cissoides. In 3Iomordica 

 Charantla and Actinostemma racemosum it is especially noticeable, 

 that the sclerenchyma at the angled portions has a double ar- 

 rangement, one mass lying just outside a primary fibro-vascular 

 bundle of the outer ring, and the other lying outside a newly 

 formed secondary bundle'^ which is placed externally to the 

 primary one. In the old stems of Trichosanthes cucumeroides, 

 T. japonica, and T. multiloba the secondary sclerenchymatous 

 cells or stone- cells are developed in great masses and form an 

 incomplete ring around the stem. 



Fihro-vasculav BurifUes, The fibro-vascular bundles in the 

 stems are arranged in two rings, the outer and the inner. Each 

 ring contains five bundles, the members of one ring being situated 

 alternately to those of the other. The fibro-vascular bundles of 

 the outer ring are smaller and nearly equally-developed, but those 



1) See below, 



