2 I 2 
James Small. 
fruit and taking the reading. From 113*5 cms. to 173*5 cms. the 
jumps decreased in length, and after 213*5 cms. the fruit lay where 
it fell with no further movement. 
As the rate of fall in quiet air 'is about 1 m.p.h. and the wind 
after 173‘5 cms. is about 1 m.p.h. the fruit would be carried a 
distance equal to that of the fall, if the wind had no other effect 
than that claimed by Praeger. The diameter of the tube is 4-5 
cms. and the length of the fruit about 1cm., so that the distance 
of the fall is about 3-5 cms. It will be noticed in Table X that 
203’5 cms. is the last point at which the fruit is carried to a distance 
which is greater than the diameter of the tube. The next reading 
gives a distance of 3-4 cms., and at this point it can be assumed 
that the fruit falls as it would in quiet air. There is considerable 
irregularity in the readings when the wind falls below 1*2 m.p.h. 
and all that is claimed as really accurate is that a wind of more 
than 1*01 m.p.h. blows the fruit further than it would do if it had 
only the effect of mass transport at the speed of the wind as 
suggested by previous investigators. Below 1*01 m.p.h. the distance 
travelled by the fruit varied from 0 to 4 cms. 
The two points to which particular attention has been paid 
are:— 
1. The least wind-pressure necessary to blow the fruits right 
through the tube with no stop and without the fruit touching tne 
tube in any way ; this is referred to as the critical pressure A. 
2. The highest wind-pressure which could be used without 
moving the fruit once it had fallen ; this is referred to as the 
critical pressure B. 
These two points are marked in Table X at ’0107 gms. per 
sq. cm. and *0026 gms. per sq. cm., and their significance is discussed 
in Section C. Other fruits are examined more or less in the same 
way, and the results are summarised below. 
Senecio vulgaris , L. Material collected in the open; the 
R.H. was *77. 
Critical Pressure A—*0055 gms. per sq. cm. P48 m.p.h. 
Critical Pressure B—*0035 „ ,, 1*18 ,, 
Senecio vulgaris , L., var. radiatus erectus, Trow.—Authentic 
material for which I am indebted to Professor A. H. Trow. It was 
found that whereas the pappus remained expanded in the air after 
being dried in a warm tube with the R.H. as high as *75, it closed 
at once when taken out of the tube with the R.H. *80. Several 
