158 PERIODICITY IN THE GROWTH OF SUGARCANE 



uiiiforin maximum, and this is maintained during active growth. Towards 

 the end of the season, however, the sheaths again diminish in length. He 

 made a distinction between the actual growth of the young internodes, and 

 their "apparent " growth as judged by the observation of the leaf joint, and 

 showed that, while the difference between the actual and apparent grow^th is 

 small during the period of full growth of the cane plant, it is large at the 

 beginning and the end of the season. Kamerling then tried a method of 

 measuring the growth of the stem directly, by removing the leafy mass 

 around the actively elongating portion, marking it and covering it with tin 

 foil, and measuring it again after 24 hours. The results agreed with those 

 already obtained, showed that the region of elongation was confined to few 

 joints, and that, in these, the top of each joint ceased growing first and the 

 lower part continued elongating after the upper had ceased to alter, that is, 

 that the region of most active growth in length in each joint was basi-petal. 

 But such harsh treatment of the young growing parts soon introduced 

 irregularities in development, and Kamerling's main results depended on 

 the indirect method mentioned above. 



To Kuijper belongs the credit of overcoming once and for all these difl&- 

 CLilties. After trying various methods, he hit upon the ingenious plan of 

 piercing the whole growing shoot with a darning needle (finer instruments 

 encountered too much resistance), starting with a full-grown leaf sheath on 

 the outside, which showed no further movement, and working upwards. 

 A series of holes were thus made through the whole mass of growing 

 parts, and, as growth took place, these holes were pushed up in various degrees 

 in the different organs inside. After a period of six days the relative position 

 of the holes was studied, and their change in position gave an accurate measure 

 of the gro\Hh which had taken place in each organ. By a multiplication of 

 the initial holes at distances of about one centimetre up the outer leaf sheath, 

 he was able to state definitely in what part of each organ growth was most 

 rapid, as all that remained to be done was to dissect out the mass after a 

 stated interval, lay out the parts, and measure the vertical distances between 

 the holes. While this method was found to disturb the growth in very young 

 parts, it fully justified its use, and the general results obtained by Kamerling 

 were substantiated, but, by a series of actual, in place of inferred, measure- 

 ments. The basi-petal tendency of the zone of most active growth in each 

 internode was confirmed, and it was found that the leaf sheath and lamina 

 behaved in a similar manner. Kuijper's w^ork was, in the main, instituted 

 for a study of certain diseases of the shoot, which appeared to depend on the 

 relative growth of the young parts, and the previous w^ork of Kamerling 



