372 



Sir J. C. Bose and Mr. G. Das. 



chamber is filled with a given gas by the working of bellows and the manipu- 

 lation of the key K ; after a given time the gas is replaced by normal air. 



Fig. 4. — P, plant-chamber ; V, V, vessels for introducing into the plant-chamber hot or 

 cold water-vapour, different gases or air, by manipulation of key, K. 



For variation- of temperature the two vessels are filled, one with hot and the 

 other with cold water. The plant may thus be subjected to a given variation 

 of temperature, by the injection of hot or cold water-vapour into the plant- 

 chamber. 



Any quick-growing organ of a plant will be found suitable for experiment. 

 In order to avoid all possible disturbing action of circumnutation, it is 

 preferable to employ either radial organs, such as flower peduncles and the 

 buds of certain flowers, or the limp leaves of various species of grasses and 

 the pistils of flowers. It is also advisable to select specimens in which the 

 growth is uniform. I give below a representative list of various specimens 

 in which, under favourable condition, the rates of growth are of the following 

 order : — 



Peduncle of Crocus 0-05 mm. per hour. 



{Zephyranthes tubispatha. Herb.) 



Flower bud of Crinum 0'07 „ „ 



Leaf of grass 1"10 „ „ 



Pistil of Hibiscus flower 1"20 „ „ 



Seedling of wheat 1"60 „ „ 



Seedling of Kysoor 3-00 „ „ 



A specimen which I found very suitable for experiments on growth is a 

 Cyperaceous plant, Scirpus Kysoor, Eoxb., locally known as Kysoor. The 

 leaves are much stronger than those of wheat and different grasses, and can 

 bear considerable amount of pull without harm. Its rate of growth under 

 favourable condition of season is considerable. Some specimens were found 

 to have grown more than 8 cm. in the course of 24 hours or more than 

 3 mm. per hour. This was during the rainy season in the month of August, 

 but a month later the rate of growth fell to about 0"8 mm. per liour. 



