C. A. lURBER 179 



(5) BlncJcening is induced by the <ijro\\'tli of a iniiuite fun<^ii.s upon the 

 bloom or waxy layer of the outer walls of tlie epidermis, and is present in all 

 canes. Although variations in blackeiiiug have not at present been studied 

 in different localities and climates, it would be natural to suppose that, where 

 there are thicker masses of wax on the stem, the blackeniuw would be more 

 widely spread and denser. This, however, does not appear to be the case, 

 although there is a considerable difference in its occurrence in the Surmabile 

 and Saretha groups. Ii\ the varieties of the latter, with large quantities of 

 bloom, blackening is fairly common, but it is rather faint and diffused, as if the 

 cane surface had been lightly smudged with soot. On the other hand, in 

 almost all of the Sunnabile group the blackening, whether abundant or com- 

 paratively scarce, is intense and sharply circumscribed, contrasting markedly 

 with the bright yellow stems. Blackening of the stem is thus a character of 

 some use in separating the two groups. 



(6) Corhj markings. These are, as already intimated, essentially splits 

 in the epidermal layers, although it usually requires a lens to determine this 

 fact. They were called " ivory markings " in Memoir 1, but the present term 

 appears to be more suitable. It appears possible that the locality in which 

 a cane is grown may have considerable influence on their development, in that 

 canes, which were noted as having very few corky markings in their native 

 habitat, have developed them copiously at CV)imbatore and rice iiersd. Corky 

 markings camiot therefore usually be considered a character of much importance 

 \\\ classification. Wlien we remember, however, the black incrustations which 

 are so uniformly present in the Saretha series and as constantly absent in the 

 Sunnabile varieties, it is worth while examining the corky markings of the two 

 groups more carefully, as in each case we have to do with the epidermal laver 

 of the cane stem. A careful study of the corky markings, in the different 

 varieties comprised in the two groups, has convinced me that there is a difference 

 in their mode of development, although this is not easy to express. For one 

 thing, these markuigs are, with few exceptions, nuich more abiuidant and 

 striking in the members of the Sunnabile group. And there seems to be a 

 difference in their mcrde of development, as will be seen from the foUowijig. 

 There appear to be three different modes of occurrence in the cane varieties 

 under ^discussion. 



(o) Long, thick, parallel lines, rather widely separated and extending 

 from the base of the bloom band about two-thirds down the length of the joint. 

 This form is practically universal '\n the Summbile series although not noted 

 in the Saretha varieties. It not infrequently happens that, ii\ a oane with 



