NECTAR AND ITS USES. 333 



flying about a mixed thicket of Cassia occidentalis and C. obtusifolia, 

 visited only the flowers of the latter. At the same time many hive bees 

 and small wild bees were seen visiting the extrafloral glands of the for- 

 mer, but none visited the flowers, nor were any humble-bees seen to 

 visit either flowers or petioles of this species. On other occasions I 

 saw hive bees, humble-bees, various small bees, wasps, ants, and moths 

 at the petiolar glands of C. occidentalis, but not one of these was seen 

 in the flowers of this species ; while in the case of C. obtusifolia, as before 

 stated, humble-bees were seen to visit the flowers, but not the extrafloral 

 glands, which appear inactive at least in Central Alabama. I also 

 found that while both the outer and inner involucral glands of the cot- 

 ton plant were visited, when in active secretion, by hive bees, but one 

 individual was seen to enter a flower ; and while humble-bees entered 

 the flowers constantly, but one was found at each set of involucral glands. 

 Humming-birds were often seen about the flowers of cotton, but none 

 were ever seen to insert their bills within the corolla, all confining their 

 visits to the glands about the flower. Their actions are somewhat 

 curious, inasmuch as a given individual visits at any one time only one 

 set of these glinds. Thus on two occasions I watched several which 

 went only to the outer set ; but on two other occasions several were 

 seen to confine their visits exclusively to the inner set. Not having 

 marked individuals, I could not, of course, determine whether a given 

 bird always limits itself to one set of glands, but I scarcely think that 

 this can be the case. 



In brief, then, we see from the examples given that nectar, wherever 

 it occurs, may be considered as excretory, reproductive, protective, or 

 nutritive ; that in some cases, e. #., 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 imma- 

 ture 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. 



OX THE HOMOLOGY AND ANATOMY OF NECTAR GLANDS. 







BRAVAIS, L. Examcn organographiqnc des nectaires. Annales des Sciences Natu- 

 relles, 1842, 2. series, xviii, Bot., 152. 



BnoxGuiAUT, A. Memoire sur les glandes nectarifcres cle 1'ovaire clans diverges fam- 

 ilies de plautes monocoty!6dones. Ann. Sc. Nat., 1854, 4. series, ii, Bot., 5. 



CLOS, D. Do la ne'cessite' de faire dispairaitre de la nomenclature botauique les mots 

 Torus et Nectaire. Ann. Sc. Nat., 1854, 4. series, ii, Bot., 23. 



MARTINET, J. Organes des se"cr6tion des ve'ge'taux. Ann. Sc. Nat., 1872, 5. series, 

 sir. Bot., 91. 



