DOGBANE AND MILKWEED. 685 



edge, into five slender points. Its deep pink veining suggests nec- 

 tar," and the insect visitor is not disappointed, for at its base are 

 five nectar-bearing glands. These stand in a ring aronnd the pistil, 

 and in a larger circle, outside the ring of honey glands, are the 

 five stamens. The anthers stand erect, and in shape are like arrow 

 or spear heads. Corresponding to the two points at the base of a 

 spear head, there are, at the base of each anther, two little hard 

 horns, and the stamens ring so closely about the pistil that horn 

 is pressed against horn all around the circle. 



On the inside of the corolla, near its base, are five triangular 

 callosities, with their points up. These are placed in such a way 

 as to alternate with the stamens, and stand a little below them, so 

 that the two hard points at the bases of two neighboring anthers, 

 and the hard tip of the callosity three little horns come to- 

 gether like the teeth of a trap. There are no fewer than five 

 places inside the flower's cup where these traps are set, and inside 

 the circle of traps are the glands which contain nectar. The 

 flower is visited by bees and flies. 



The insect caller must run his proboscis in between the long 

 anthers, and just above the horny excrescences on the corolla. 

 When he attempts to withdraw, after drinking his fill, the three 

 points lock together, like the jaws of a trap, holding the tip of his 

 proboscis in durance vile. If the winged captive is big and strong, 

 he gets free, with a long and a vigorous pull. But small flies are 

 often held prisoners till they die, probably from starvation. 

 Sometimes one may see three or four of these hapless victims on 

 one full-blooming plant of spreading dogbane. 



Among the prisoners one may often see a little summer fly of 

 dudish aspect, with body ringed with alternate bands of bronze 

 and gold, and wings of gauze shot with opaline colors. To what 

 end is this bright little fellow sacrificed ? Held as he is by the tip 

 of his proboscis, his body does not come in contact with the plant, 

 and hence it can not be digested by the vegetable juices, as are the 

 corpses of the sundew's victims. The dogbane is apparently un- 

 able to furnish any adequate justification for his taking off. 



There is another variety of dogbane, the Indian hemp, or Apo- 

 cynum cannabinum, which bears smaller blossoms than the an- 

 drosmmifolium, blooms somewhat later, and is more widely dis- 

 tributed over the country. This flower has no callosities in its 

 corolla, sets no snares for insect victims, and is apparently quite 

 innocent of the crimes which one is inclined to lay to the charge 

 of its first cousin. 



The common milkweed (Asclepias cornuti) also imprisons in- 

 sects, which sometimes die in captivity, and do no apparent good 

 to the plant by their deaths. They have, however, invited mis- 

 fortune, for though the milkweed is rich in honey, and is visited 



