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out food inducement. A longitudinal section of the upper portion of 
the pistil will show the style with the stigmatic tube, which at this time 
communicates with the ovarian cells. Now, Trelease has shown that the 
stigmatic hquor is not nectarian, but that the slight amount of nectar 
associated with the flower is secreted in pockets formed by the partitions 
that separate the three cells of the pistil, and which open externally 
near the style by a contracted pore from which the nectar is poured 
through a capillary tube to the base of the pistil. The accompanying 
illustration (Fig. 65) renders this more intelligible, a being a longitud- 
inal section through the center of a pistil, showing the septal gland (9g), 
the duct (d), and the outlet at the base; 0) a cross section of the pistil 
about the middle, also showing the duct (d), and gland (g); c, a more 
enlarged cross section of the nectar apparatus; e showing more fully 
the structure of the septal gland, while fis a longitudinal section of 
the top of the pistil, through the lobes, showing how the stigmatic tube 
(s) connects with the ovarian cell (0 ¢), o being the ovary, / the funicu- 
lus, p the placenta, and / v fibro-vascular tissue. 
These interesting facts, which I have fully verified, show that nectar- 
feeding insects seek it not about the stigma, but at the base of the 
stamens or of the petals, whether within or without. In short, the 
nectar in these Yucea flowers has no value in pollination, and Pronuba, 
in collecting the pollen and transferring it to the stigma, finds no food 
compensation, a conclusion which is confirmed by a study of the minute 
structure and internal anatomy of the moth, which indicate that the 
tougue proper, though strongly developed, has to a great extent, if not 
entirely, lost its function as a sucking organ, and that the alimentary 
canal is practically functionless, being aborted before reaching the anus. 
This defunctionization, if I may use the term, of important structures 
has not proceeded so farin Pronuba yuccasella as in P. maculata, which 
pollinizes Yucca whipplet. Those not familiar with the structure of 
Lepidoptera will hardly appreciate the modifications to which I shall 
allude, however, without the preliminary statement that the tongue in 
Lepidoptera consists of two distinct parts (maxille) which are more or 
less concave on their inner side and united at the borders of the con- 
cave portion by certain locking arrangements to form between them 
the sucking tube. Now, while in most cases the two parts may be re- 
laxed and separated by force, in nature they are never so separated, 
while the tip of the tongue is more or less acuminate and the two parts 
here very firmly united. 
In Pronuba yuccasella | had often noticed that the two parts became 
separated, and in fact were almost always separated toward the tip, 
thus suggesting the loss of function as a sucking organ, but otherwise 
the tongue is strongly developed, and, with the exception of the weak- 
ness of the locking arrangement, not particularly abnormal. In Pro- 
nuba maculata, however (Fig. 66), the two parts of the tongue are but 
very feebly united, and often more or less disconnected, and are actu- 
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