178 STUDIES IN INDIAN SUGARCANES 



(2) Stripinf/. 'Plic ()t)sorvati(»]is on this point must l)e considered incom- 

 plete , for, with only 10 to 20 canes examined, it is quite possible that the 

 character may have escaped notice, and may be only very occasionally present. 

 Striping has not been met with in any of the Katha section of the Saretha 

 group, four out of seven of the Mesangan section have showji it, while it has 

 been noted, usually with great ease, in fourteen out of fifteen of the Suiuiabile 

 group, Dhaulu alone appeariiig to be without it (in the observations recorded). 

 This striping is ext.remely faint and consists of fij\e purple lines on the lower 

 parts of the canes. 



(3) Blnck incrustafiom. This is a marked character in all the varieties 

 of the Saretha grouj) and is totally absent in the Suimabile series. It is there- 

 fore a prime character. Its nature has long been a puzzle, but a series of sec- 

 tions have demonstrated that it is caused by the ei\largement and protrusion 

 of certain epidermal cells whose contents assume a brown and ultimately 

 charcoal black colour. It is an obvious roughness on the surface and hence 

 has the appearance of an incrustation, and was at first thought to be caused 

 by the bites of minute insects or mites ; but no exuviae of any kind have been 

 found. It occurs typically in the groove — -which is absent in the Siuumbile 

 group — but may extend to all part,s of the joint, and sometimes occurs in such 

 masses that it gives a characteristic colouring to the whole cane, especially in 

 its upper part.. It is worth while recording that a similar black or brown 

 incrustation is very commonly met with on the stems of Saccharum spontanemn, 

 including the Dacca water form. 



(4) Bloom. The waxy layer of the epidermis apj^ears as thick layers of 

 bloom in the Saretha class, especially in upper parts of the canes. It is some- 

 times difficult to make out the limits of the bloom baiid, because of the extent 

 to which this layer of bloom descends over the joint, and it is not imcommon 

 for the whole upper part of the cane to become grey or even white because of it. 

 The Katha section has more bloom than the Mesangan and this adds to the 

 differences of the two sections in colour. The bloom bands, excepting in the 

 case noted above, are rather distii^ct in the group, but become obscured by 

 weathering in the lower parts of the cane. In the Smmabile grou]) the bloom 

 is not heavy and it descends over the cane surface to a much less degree. The 

 bloom bands are not usually so conspicuous, but this is partly due to the 

 yellow colour of the caiies ; in Pnlli Khajee, a bright green cane, the bands 

 stand out very distinctly. The quantity of bloom on the canes of the two 

 groups varies very consistently and this character is therefore one of some 

 importance, , 



