THE ASCENDING SAP 



113 



developments of the petiole, or leaf-stalk, 

 their lids (where lids are formed) probably 

 constituting the blade. 



We may begin with the Sarracenias, 

 popularly known as Indian Cups, Side- 

 saddle-flowers, and Trumpet-leaves. In fig. 

 152 we have the beautiful but treacherous 

 Sarmcenia flava, which bears a magnificent 

 flower of a rich canary-yellow, sometimes 

 measuring as much as eight inches in 

 diameter. The long trumpet-shaped erec- 

 tions are the leaves, which have been united 

 at their margins to form pitchers (though 

 some regard these pitchers as hollow leaf- 

 stalks), and which usually contain a fluid 

 not rain-water of a bland and somewhat 

 mucilaginous taste. In the photograph 

 (fig. 151) is shown a mass of organic matter 

 at the base of the tube, consisting of clotted 

 flies in all stages of digestion and decay. 



Professor Asa Gray, the distinguished 

 American botanist, studied these plants 

 closely, and has given an amusing account 

 of what takes place inside the long pitchers 

 when once they have been entered by 

 insect visitors. " After turning back the 

 lids of most of the leaves," he writes, " the 

 flies would enter, a few alighting on the 

 honeyed border of the wing, and walking upward, sipping as they went 

 to the mouth, and entering at the cleft of the lower lips ; others would 

 alight on the top of the lid, and then walk under the roof, feeding there ; 

 but most, it seemed to me, preferred to alight just at the commissure of the 

 lips, and either enter the tube immediately there, feeding downward upon 

 the honey pastures, or would linger at the trunk, sipping along the whole 

 edge of the lower lip, and eventually near the cleft. After eating (which 

 they generally do with great caution and circumspection), they begin again 

 to feed, but their foothold, for some reason or other, seems insecure, and 

 they occasionally slip, as it appears to me, upon this exquisitely soft and 

 velvety declining substance. The nectar is not exuded or smeared over 

 the whole of this surface, but seems disposed in separate little drops. I 

 have seen them regain their foothold after slipping, and continue to sip, 

 but always slowly and with apparent caution, as if aware that they were 

 treading on dangerous ground. After sipping their fill they frequently 

 remain motionless, as if satiated with delight, and, in the usual self- 

 11 



FIG. 147. PITCHER OF Nepenthes. 



The pitcher is here cut through to show what 

 happens to insects when they venture inside. 



