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Mr. F. Darwin and Miss D. F. M. Pertz. [May 30, 



symmetrical distribution.* Our experiments tend to confirm this point 

 of view, since they show that the statoliths are not evenly dispersed 

 through the cells,! but that they take up more or less definite 

 positions in different parts of the rotation. The experimental plants 

 were, as before, seedlings of Setaria and Sorghum, cemented into boxes, 

 or fixed between cork and damp blotting-paper, and so arranged that 

 the axis of the plants were at right angles to the axis of rotation. 

 The klinostat, which made one revolution in 17, 20, or 30 minutes, 

 was placed in a dark room, where the temperature varied from 

 17 to 24° C. The number of seedlings used in each experiment was 

 four, six, or eight, and, in all cases, half the number pointed in one 

 direction, and the others in the opposite direction. Thus, at the 

 moment at which the seedlings are vertical, half of them are " apex 

 upward," the rest being apex downwards. The method was to leave 

 them rotating on the klinostat, and to remove them the moment they 

 reach the vertical, when the starch in the two lots (up and down) was 

 rapidly compared. With a rotation of once in 30 minutes, the 

 apex-upward seedlings will have been for 7J minutes passing from the 

 horizontal to the vertical. With the 17 and 20 minute klinostats, the 

 periods will be respectively 4J and 5 minutes. It will be seen in 

 Table V that, in the first three experiments in which the duration of 

 the rotation was short, no definite result was obtained ; and the same 

 absence of difference in the starch was noted in two other experiments 

 in which the plants were examined, after two rotations of 17 minutes. 

 In the remaining experiments a distinct result was obtained. 



In a few experiments given in Table VI, the klinostat was stopped 

 when the seedlings were horizontal. In this case half the seedlings 

 ("apex last down") had for 4 J minutes been changing from apex 

 vertically down to horizontal, while the other lot ("apex last up") 

 had changed from apex up to horizontal. These experiments, taken 

 with those in Table V, show that a complete reversal of the starch 

 from the apical to the basal ends of the cells may take place on the 

 klinostat in 8J minutes. 



Table VI also gives the results of three experiments, in which the 

 seedlings were parallel to the axis of rotation, in two of which the 

 starch was, as was expected, on the longitudinal cell walls (" lateral "). 



On the whole, the results of Tables V and VI show that there is 

 no inconsistency between the statolith theory and the view above 

 referred to, that continuous gravitational stimulation occurs on the 

 klinostat. 



The question whether 8J minutes, the period during which gravi- 



* See Elfving ' Ofversigt af Finska Yetenskaps Forhandlingar,' 1884, and 

 F. Darwin on " Cucurbitous Seedlings," ' Practical Physiology of Plants,' 1st 

 edition, 1894, p. 176. 



t As Jost, loc. cit., p. 176, seems to believe to be the case. 



