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 a . 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 stigmatic 



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

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

 !ater, showing the pollen-masses deflexed. 



