504 Harris. — On a Chemical Peculiarity of the 
excess of that lost by the yellow. In the illustrative series B-G the anthers 
were more nearly completely air-dried. The results are : 
Experiment. 
B 
C 
D 
E 
F 
G 
Percentage loss of Red. 
73*67 
73*35 
74-00 
75*°5 
74*74 
73‘ 2 9 
Percentage loss of Yellow. 
74-02 
74*55 
73- 70 
74- 04 
75*i6 
74-20 
In view of the technical difficulties involved, no significance is to be 
attached to these differences . 1 The density of the two types of anthers 
may be taken as about the same. Their volume may be regarded as 
directly proportional to their weight. The average weights are : 
Series. 
B 
C 
D 
E 
Mean weight of Red Anthers . 
. . 0-000990 
. . 0-000950 
0-000926 
. . 0.000993 
Mean weight of Yellow Anthers. 
0-000705 
0-000740 
0-000743 
0-000723 
Thus there is a considerable difference in volume, which means 
a considerably lower ratio of surface to volume in the red anthers. 
This should, on purely physical grounds, be followed by a lower rate 
of evaporation from the large anthers. Instead, a higher initial rate 
obtains. 
Besides these convincing evidences against the physical nature of the 
physiological peculiarities of the anthers, there are many indications that 
there is some chemical substance in the small anthers which by its 
presence (or by its relatively greater abundance as compared with the large 
anthers) limits the loss of water. The data upon which this statement is 
based are drawn from experiments in the loss of water, and from those on 
the reabsorption of water by anthers which had been washed or boiled in 
water, or extracted with alcohol and ether and dried. These experiments 
I do not care to describe in further detail, since I believe that the difficulties 
incurred were beyond our skill, and that the quantitative data we secured 
are not worth publication. That the results are due to some substance 
occurring only, or in much greater abundance, in the smallest anthers, I have 
not the slightest doubt. 
V. Ecological Relationships of Flower. 
Bees were observed as visitors, collecting pollen from the small yellow 
anthers, but as far as could be observed, almost without exception, taking 
no notice of the large ones, which are of a colour very similar to that of the 
unguiculate petals. The following species, kindly determined by Mr. Charles 
1 Drying on a bath gives a higher percentage loss of water, but there is no clear evidence from 
several determinations that there are any constant differences in the relative water content of the two 
types. 
