14 ART. 1. — A. YASUDA : ON THE 



with a circular contour ; — all wliicli structures characterize the 

 above organs of Melothria japonica aiicl Gyinnostenima cissoides 

 as such respectively.^^ The rhizomes serve as a reservoir of 

 food-materials, so that though other parts of the plants perish 

 with the approach of winter they preserve their life till the next 



spring, when the young plants grow from the rudimentary scales 

 destined to be the shoots ; thus Jleloihria japonica (PL II. Fig. 

 37) and Gymnostemma cissoides lead a perennial life by means 

 of their subterranean stems. 



Generally speaking, the anatomical structures of the rhizomes 

 follow the type of the terrestrial stems, but in particulars they 

 differ widely from the latter. The collencliyma is reduced to a 

 trace, or can be no longer distinguished as such. Jn Jlcloihria 

 japonica a very snudl group of the delicate sclerenchymatous cells 

 is found only on the outside of each fibi'o- vascular bundle of the 

 outer ring, while in Gijmnosicmina cissoides the degeneration is 

 not so great as in Melothria japonica ; the sclerenchymatous cells 

 composed of "2-5 layers, extending outside of each libro-vascular 

 bundle of the outer as well as of the inner rings. 



The libro-vascular bundles in the rhizomes show great de- 

 generation. The sieve-tubes and the vessels are much smaller 

 than those of the terresti'ial stems. The following are the diameters 

 of the large sieve-tubes and vessels in the rhizomes of Meloihria 

 japonica and Gymnostemma cissoides : 



8ifvc-luli(_'. Vessel. 



Melothria japonica 0.032 mm. 0.07 mm. 



Gymnostemma cissoides 0.031 ,, 0.12 ,, ; 



from which we see that the degeneration is nuicli greater in 

 Meloth'ia japonica than in Gymnostemma cissoides. 



1) Compare p. 9. p. 20. and p. 33. 



