260 THE PI.ANT WORLD 



stamens of the male flowers and the viscid fleshy red pistils of the female 

 flowers, which are cleft at the tip. On the serrations of the young 

 unfolding leaves there were minute waxy glands — also nectaries, in all 

 probability. The wasps would go from nectary to nectary — from the 

 glands on the nodes to those along the petioles and to the large pair at 

 the base of the peltate leaves. Watched them chase away some flies and 

 other insects which were also attracted by the sweet excretion of the 

 glands. The tender opening leaf-buds were studded with nectaries. In 

 noticing them I was immediately struck with the thought that it would 

 not be well for caterpillars or other insects to try to eat them while the 

 wasps were upon them ; and then I noticed that not a leaf of the plant 

 showed evidence of having been attacked by insects. Possibly in the 

 original home of the species it had enemies which were repelled by the 

 wasps or ants who were attracted by the nectar of its glands. The whole 

 subject of the occurrence of nectar in flowers and on leaves and other 

 parts of plants is interesting. I have already noted the occurrence of the 

 glands in the midribs of some of the Malvaceae and L,eguminosae grow- 

 ing on this island. (Entrj^ in Note-book, September 19.) To-day I also 

 noticed the glands at the base of the veins of coffee leaves.* 



Since writing the above my attention has been called to a most inter- 

 esting paper by Trelease on "Nectar, its Nature, Occurrence, and Uses," 

 which is embodied in the Report on Cotton Insects by J. Henry Comstock, 

 U.S. Department of Agriculture. This paper was called forth by the 

 importance of the nectar glands of the cotton plant in their influence upon 

 the natural enemies of the cotton and boll worms. The nectaries of the 

 cotton plant, of Marcgravia nepentJioidcs , and Poinsettia pulcherrima are 

 figured as well as those of Ricimis comnuinis ; and Mr. Trelease gives an 

 extensive bibliography of works on nectar glands, on insectivorous plants 

 which attract their prey by nectar, on the animals which seek floral nectar, 

 and on the fertilization of flowers in general. In summing up the results 

 of his researches he says that " nectar, wherever it occurs, may be con- 

 sidered as excretorj', reproductive, protective, or nutritive ; that in some 

 cases, <?. g., the leaves of the peach, excretory nectar may possibly be 

 protective also ; that reproductive nectar usually occurs in the flowers but 

 not always ; that protective nectar seems in some cases designed to keep 

 ants from defoliating and deflouring the plant ; in others, to keep larvae 

 from destroying the foliage or immature fruit ; that nutritive nectar may 

 serve in some cases to lead to the capture of wingless, in others of winged, 

 insects ; and finally that the vital force of a plant is taxed so little in the 

 production of nectar that glands once developed and endowed with the 

 power of active secretion may continue to secrete for generations after 

 the necessity for their secretion has ceased to exist." (Op. cit., p. 333.) 



♦ For illustrations of these glands see Plant World, 6 : 128, June, 1903. 



