15G PERIODICITY IN THE GROWTH OF SUGARCANE 



import auce of the subject from tlio factory point of view has barely been 

 realized. Kobusi (1887-1893) made a study of the growth in length of the 

 lamina, and gave details as to the extent to which the imier structure was 

 completed in leaves of different length. He pointed out th.at the lamina 

 attained its full growth far sooner than the sheath- We have not had the 

 opportunity of seeing Kobus's papers, and quote this from that of Kuijper 

 mentioned below. Kamerling^ issued an important paper in 1904, and quite 

 recently Kuijper^ has returned to the subject in 1915, and these papers deserve 

 careful reading. 



One of the greatest difficulties in measuring growing canes is due to the 

 fact that the portion in actual elongation is permanently enswathed in a mass 

 of leaves which cannot be removed without disturbing the growth. Observg- 

 tion of the ends of these leaves cannot be used in measurement because of the 

 constant variation in length of successive leaves during the growing period. 

 It becomes necessary to find some definite external point on the shoot which 

 bears a constant relation to the growing point of the stem within. Kamerling 

 set himself to find such a point. His object was to study the rate of gro\\i;h 

 in different fields and varieties, and to replace the general terms in use, such 

 as "rapid," "slow," "moderately slow," and so on, by exact measurements, 

 at the same time pointing out the importance of such work for the factory. 

 By determining the rate of growth under certain well-defined conditions, he 

 claimed that we should be in a position not only to decide the fitness of a 

 variety for its locality but also to fix on general measures whereby unsatis- 

 factory growth might be remedied. He first of all found that there is a 

 sequence of growth in length in the lamina, leaf sheath and stem of a very 

 definite character. The lamina first grows in length, rapidly unfolds itself 

 and ceases from any further increase ; as soon as this is completed, the energy 

 of growth is transferred to the sheath. It quickly elongates and pnshes the 

 lamina into the air and light and, in its turn, ceases from further growth in 

 length. Lastly, when the leaf sheath has finished growing, the stem inter- 

 nodes, hitherto merely a series of flat, superposed discs, suddenly elongate by 

 the expansion of their cells and cease to grow in length after a very short 

 time. The sheaths thus complete their growth in length before the internodes 

 commence to elongate, and their further apparent growth is due to the increase 



1 Kobus, J. D. Bijdrage tot de kennis van den bouw en de ontwikkeling van het suikerriet , 

 I and II, Nos. 19 and 30 of the Mededeelingen van het Proefstation Oost-Java, 1887-1893. 



2 Kamerling, Z. De lengtegroei van het riet, Archief voor de Java-Sxiikerindustrie, deel 

 XII, 1904, page 997. 



' Kuijper, J. De groei van bladschijf, bladscheede en stengel van het suikerriet, Mededee- 

 lingen van het Proefstation voor de Java-Suikerindustrie, V, 8, 1915. 



