150 BOTANICAL GAZETTE [august 



starch is neither. The latter naturally tends to disappear from all 

 parts while the grain is filling, and it is therefore a fact to be noted 

 that the statolith starch is unaffected by this drain on the stored 

 food material, and therefore cannot be regarded as primarily 

 nutritive in function. 



Both Darwin and Haberlaxdt have referred to the " falling 

 time" (i, p. 771), and "period of migration" (2, p. 598) of stato- 

 liths, but I am not aware of any work on the rate of travel other than 

 my own, which is not yet published in full (6). The unique feature 

 Of the wheat plant in possessing two kinds of statoliths, together 

 with its extreme economic importance, perhaps justify a separate 

 - statement at the present time. Experimental work has demon- 

 strated the fact that the rate of travel of the crystal is much greater 

 than that of the starch grain, for the latter falls at about 120 /x 

 per hour, while the rate of the former is nearer 600 /x. 



The rate of the starch grain approximates to that obtained i 

 the movable starch grains in the inflorescence axis of Lupinus, a: 



probably very average, but 600 fi per hour 

 ereat as that of anv statolith known to me 



from 



er is probably under 5 minutes 

 grain varies with the diameter ( 





minutes. In nature, however, since the 

 displaced more than 90 from the vertical, 

 t traverse the whole diameter of the cell, 



some 



time 



1m 



means 



gravity (1, 2) , it is the latter period which is of biological im 



becomes interesting 



on record. The wheat is capable of bending at the nodes in order 



haulm 



energy 



same time both sensory 



motor, that is, capable of perceiving 

 appropriate stimulus. 





