20 



tracante" Riviere's. We shall not, however, continue longer the less 

 fruitful discussion of external characters, but turn to examine the anatomical 

 structure. 



Internal Structure. 



It is hardly necessary to mention that the anatomical method may 

 render a useful service to the classification especially by such a group as 

 Bambuseac, where we encounter a great deal of difficulties in the way of 

 classifying merely according to external characters. Yet it must be borne in 

 mind that we must be very careful to distinguish among the anatomical 

 characters the physiological ones, which are usually constant only to a species, 

 and the phyletic ones, which are available as indications of relationship of 

 the members belonging to certain genera or tribes.-' From this point of 

 view the structural variations of the rhizomes, 3) or more exactly the different 

 modes of arrangement of the mechanical tissues in the rhizomes seem to be 

 the characters belonging to the former category ; for instance we behold 

 amongst the genus Phyllostacltys that the thick stout rhizomes of P. mitis, 

 P. bambusoides, etc., are devoid of any other mechanical elements except 

 the bundle sheaths, while the slender rhizomes of P. Kumasasa require, as 

 they do, the development of a complete subcortical sclerenchyma-ring to 

 strengthen its firmness against bending. The anatomical structure of the 

 culms and leaves affords, on the whole, so uniform an appearance through- 

 out the representatives of several genera and subtribes, that it seems very 

 difficult to secure any salient feature available fur the purpose of classification. 

 On the contrary we find just in the root-structure a valuable means in this 

 respect. 



The peculiar structure of the roots of some bamboo- plants has already 

 been pointed out by Ross, 4) whose observations we are now able to confirm 

 and to extend to several representatives of the Arundinarieaj, Eubambuseai 

 and Dendrocalainea?. As far as our present knowledge reaches, the peculiar 

 root-structure, i.e., the presence of internal xylem- and phloem-strands in the 

 axial cylinder seems to furnish, amongst the monocotyledons, mostly the 



1) Ri vi&re, loc. tit. 



2)Solereder, System at ische Anatornie d. bicotyledonen. 1899. p. 7. 



3) K. Sh ibata, Eeitriige z. Wachstumsgeschichte d. Bambupgewachse. Jour. Coll. Sc. Imp. 

 Univ. Tokyo, Vol. XIII, pt. 3, p. 433. 



4) Ross, Beitrage z. Anatornie abnormer Monocotylenwurzeln. Ber. d. D. Bot. Gesells. 

 Bd. I, p. 336. 



