178 PERIODICITY IN THE GROWTH OF SUGARCAXE 



four, veT'y late canes, have few maxima, and their dotted line suggests that 

 these synchronize with the later maxima of the preceding canes. If this 

 reasoning has any foundation, we have a distinct suppoit to the argument 

 that the general curves of maxima in tlie twenty canes represent a succession 

 of synchronous growth stimuli, which. afiVct all the canes growing at the time, 

 in other words, that the cause of the stimulus is external. We have been 

 accustomed to look to the Pansahi group of canes for clearing up our ideas on 

 many of the pro(;esses of growth in the sugarcane plant^ and this would 

 account for their showing this periodicity in growth better than in the other 

 varieties examined. We have, in the above reasoning, merely attempted to 

 show a possible explanation of the peculiarities in the position of the 

 maxima of joint length. For any certainty to be attained as to the cause 

 of this periodicity, whether external or inherent, the piesent observational 

 method does not yield sufficient data. A simple series of experiments 

 should be capable of determining the point at issue. 



Of the dozen or so examples worked out, three others are added, in which 

 the periodicity in the length of the joints of the cane is observable (Plates VII 

 and VIII). Two of these are from Pansahi plots in the wet lands on Coimba- 

 tore Farm. In these, the numbers of joints are few and there are also few 

 maxima. The periodicity, as explained above, is however distinctly visible, 

 especially in the case in Plate VII. The variation in the number of joints in the 

 twenty canes is small, and the end dotted line is accordingly more vertical 

 than in the former case, and this uprightness of the curve is reflected in the 

 general maxima curves of each series. 



The last example is of Baroukha canes grown at the Cane-breeding Station 

 in 1915-16 (Plate VIII, fig. 2). There are a large number of joints, and great 

 variations occur in the twenty canes in this respect. There are also many 

 maxima noticeable in individual canes. Although these are by no means so 

 regularly placed as in the PansnJii canes, there is a distinct suggestion of 

 periodicity in many cases. This is fairly obvious in the first eight canes and 

 in the last six, but there are few maxima in the intervening six, and it is not 

 possible to introduce connecting lines in them. There is, moreover, a lack of 

 parallelism, in the diagram, between the connecting lines and the end dotted 

 line. For instance, in Canes Nos. 1-3, with the same number of joints although 

 the connecting lines are more or less parallel, they trend strongly to the left 

 instead of being vertical. In Canes Nos. 3-5, an opposite direction is assumed, 

 the end lines passing down to the left while the connecting lines pass to the 



1 Barber, C. A. Studies in Indian Sugarcanes, No. 4. Tillering of Underground Branch- 

 ing. Mem. Dei^ Agric, Ind., Dot. Ser., Vol. X, No. 2. 



