604 ON THE HAIR-COLLECTORS 
completely into the imbedded cavities as to be scarcely visible 
above the surface of the style. In this state they exhibit a 
truncated extremity. To restore them to their original shape 
and dimensions, nothing more is requisite than to lay a thin 
longitudinal section of the style in a drop of water under the 
microscope and gently to press the bases of the pollen-col- 
lectors, when they immediately protrude themselves, pushing 
before them, not unfrequently, the grain of pollen which in 
the act of retraction had been drawn into the cavity, as 
Brongniart has accurately recorded. These pollen-collectors, 
when thus restored, are found to possess both the membranes 
unaltered. In their perfectly retracted state, the apex is 
certainly not visible, but it may be made to project in any 
degree by the application of carefully adjusted pressure. 
The preceding observations lead forcibly to the conclusion 
that there is an essential communication between the pollen- 
collectors and the ovarium ; and this conclusion is not weak- 
ened by an attentive examination of the structure of the ex- 
ternal zone of the style and stigmatic branches. The cellular 
tissue which surrounds the cavities for the reception of pollen 
is obliquely packed in lines sloping downwards towards the 
ovarium and the vascular tissue at the summit of the style 
divides into numerous branches, which have an outward di- 
rection towards the most energetic pollen-collectors. My 
purpose, however, is not to propound a theory, but to record 
facts, and to excite other and more skiful observers to pur- 
sue the same path of inquiry to its consummation. 
REFERENCES TO THE FIGURES. 
(Tas. XX. B). 
Fig. 1, section of a pollen-collector, showing the two mem- 
branes, including three grains of pollen, magnified; f. 2, 
section of a bierg with two grains of pollen, 
ore highly magnified; f. 3, section of a portion of the 
style, showing the alten and the cells or cavities 
