100 



RauwenhofPs observations agree with mine on Nehimbo, so far as the 

 day and night growths are concerned, the day growth being greater than 

 that in the night. . But he found, as is shown by the above table, that 

 the growth in the forenoon is less than that in the afternoon, while in 

 my observations the maximum growth is attained in the forenoon. 



Recently, G. Kraus lj has made observations on the growth of the 

 bamboo-cane in Java. According to him, the growth of bamboo is faster 

 at night than in the day. Thus, he gives the hourly growth in m.m. for 

 day and night as follows. 



Shoot II. 4 Dec. 5 Dec. 6 Dec. 7 Dec. 8. Dec. 9 Dec. 



Day 15.4 6.6 8.4 2.9 9.2 6.3 



Night 12.4 13.0 16.6 12.1 17.5 13.8 



Shoot III. 



Day 3.8 3.8 6.6 7.1 10.0 8.3 



Night 13.3 12.5 13.3 10.2 11.0 10.4 



He also calls attention to the growths in both fore-noon and after-noon. 

 But the ratios of these were variable, sometimes the one, sometimes the 

 other being greater. 



More recently, Walter Maxwell 23 has made observations on the growth 

 of banana leaves in Hawaii and has found that the elongation of the leaf 

 about twice as much in the day-time as at night. 



Thus, the ratio of growth for day and night and also fore and after- 

 noon is very variable, according to the external as well as the internal 

 conditions of the individual plant. As is generally acknowledged the 

 difference of the rate of growth by day and night is caused by complex 

 factors which are partly due to the change of external conditions, but 

 partly also to the fixed or rather inherited properties peculiar to each 

 species. Of course, it should not be concluded that the acceleration of 

 growth in the day-time is entirely due to the higher temperature then 

 than in the night, but that other factors must co-operate at the same 

 time : thus, the influence of the first warm ray of the morning sun 

 combined with the after-effect (Nach-wirkung) of the darkness during 

 the night may act as the stimulus which tends to cause the quick 

 growth of the plant-body in the morning hours. Moreover the peculiar 



1) Physiologisebes aus den Tropen : I. Das Langenwachsthum der Bambusrohre. Ann. 

 <lu JarcL Bot. de Buitenzorg. Vol. XII, 1895. 



2) The rate and mod' of growth of Banana leaves. Botanisches Centralblatt, Bd. LXVII. 

 1806, and also Botanical Gazette, Vol. XXI, 1896. 



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