ADAPTATIONS FOR INTERCROSSING. 



233 



flower so that its proboscis may reach and drain the bottom of 



the nectariferous tube, a pollen-mass will usually be affixed to 



each eye : on withdrawal, 



these will stand as in Fig. 



466. Within a minute they 



will be turned downward 



(Fig. 466"), not by their 



weight, but by a contraction 



in drying of one side of the 



thick piece which connects 



the disk with the stalk. 



When a moth in this con- 



dition passes from the last 



open flower of one spike to 



that of another plant, and 



thrusts its proboscis down a 



nectary, the transported pol- 



len-masses will be brought 



in contact with the large 



glutinous stigma : on with- 



drawal, either some of the 



small pellets of pollen will be 



left adherent to the stigma, 



the connecting elastic threads 



giving way ; or else a whole 



pollen-mass will be so left, 



its adhesion to the glutinous 



stigma being greater than that of the disk to the moth's eye. 



The former is a common and a more economical proceeding, as 



then a succession of flowers are abundantly fertilized by one 



or two pollen-masses. In either case, new pollen-masses are 



carried off from fresh flowers and applied to the fertilization 



of other blossoms on the same and eventually on those of differ- 



ent individuals. Cases like this, and hundreds more, all equally 



remarkable, serve to show how sedulous, sure, and economical are 



the adaptations and processes of Nature for the intercrossing of 



hermaphrodite flowers. 



422". An arrangement analogous to that of Orchids, and 

 similarly subservient to cross-fertilization, characterizes the 

 otherwise widely unlike Asclepias family. In Asclepias (Milk- 

 weed) there are five stamens surrounding a large stigniatic 



401, <* 



FIG. 466. Front part of Sphynx drupiferarum, bearing a pollen-mass of Platan- 

 thera orhimlata affixed to each eye, in the early position. 466 . Front view of the head, 

 later, showing the pollen-masses deflexed. 



