COMPARATIVE ANATOMY OF THE CUCUFtBITACEJ!:. 4-5 



cells are remarkably small, but in Actinostemma racemosum and 

 Momordica Cliarantia they are exceptionally large. 



The number of the layers of the hypodermal cells outside of 

 the hardened ring should also be noticed. While usually they are 

 many-layered in Jlelothria japonica and Gijmnoüemma cissoidcs 

 they are reduced to the minimum ; that is, in the former tlie 

 hypodermal cells are one- or two-layered, l)ut in tlie latter only 

 one-layered. 



Ffhro'Vasculnr Bun files. As a rule the fibro- vascular 

 bundles in the fruit are weakly developed, and most of them have 

 no sclerenchymatous sheath. Exceptions are found, however, in 

 the fruit of Luffa cylindrlca and L. acutancjuln. The fibres con- 

 stituting the net-work of the X^(^«-fruit are really the fil^ro- 

 vascular bundles surrounded by the thick layers of the scleren- 

 chymatous cells, which give a roundish shape to the fibres, and 

 make them extremely elastic, the circumscribed bundles themselves 

 remaining merely rudimentary (PI. V. Fig. 59). 



A peculiar arrangement of the fibro-vascular bundles is observed 

 in the tubercles on the surface of the fruit of Momordica Gharantia. 

 A bundle enters into the tubercle perpendicular to the surface of 

 the fruit, briinching out near the top of the tubercle (PI. IV. 

 Fig. 5(j). 



The sieve-tubes show a characteristic distribution in the fruit- 

 tissue. Besides those found in the phloem, there occur isolated 

 sieve-tubes in the tissue of the pericarp within the epidermis (PI. 

 V. Fig. 61). In the species which have the hardened ring such 

 as Benincasa cerifera, Trlcliom.nilies cucunieroldes, T. japonicri 

 and T. midtiloha, they occur in the hypoderma on the outside of 

 the ring, and in Hchr^opeiioii hnjonhrfollus, v(tr. j<t[)oniciis, Cucumis 



