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Show 434 HABITS OF INSECTf:l. CHAP. XI. had many flowers perforated ; but I found throe plants in separate parts of the garden which had sprung up accidentally, and these had not a single flower perforated. General Strachey formerly saw Inany perforated flowers in a garden in the Ilima1aya, an<l he wrote to the owner to inquire whether this relation between the plants growing crowded ttncl their perforation by the bees there helJ. good, and was tUtBwored in the affi.rn1ative. Hence it follows that tho rod clover (Trifolium pratense) and the common bean when cultivated in great n1asscs in :fielcls,-that Erica tetraliaJ growing in large nuinbors on heaths,-rows of the scarlet kidney-bean in the kitchen-garden,-an<l masses of any species in the :flower-gardon,-aro all mninently liable to be perforated. The explanation of this fact is not difficult. Flowers growing in largo ntnnbers afford a rich booty to the bees, and arc conspicuous frmn a distance. rrhoy are consequently visited by crowds of those insects, and I once counted between twenty and thirty bees flying about a bed of Pentstemon. rrhey are thns stin1ulated to work quickly by rivalry, and, what is much 1nore important, they find a large proportion of tho flowers, as suggested by Iny son,* with their nectaries sucked dry. rrhoy thUS waste n1 UCh time in searching 1nany m pty flowers, and arc led to bite the holes, so as to find out as quickly as possible whether there is any n ctar present, and if so, to obtain it. Flowers which are partially or wholly sterile unless visited 1y insects in the proper n1anner, such as those of most species of Sal via, of Trifoli~~?n pratense, Phaseolus multiflorus, &c., will fail n1ore or less completely to prod~1ce seeds if the bees confine their visits * 'Nature,' Jan. 8, 1874, p. 18D. 0HAP. XI. PERFORA'riON OF ; TilE COROLLA. 435 to th· e perf.o rations · The perf 'o ra ted fl species, which are capable of~ ·t·l· . owcrs of those yi.e ld on 1y self-fertilised dle i I Isinoa the mse 1v es, W.i ll . see s and the dl. In consequence be loss V.I n-orous' . . Th . £ se. e In!rs will u must suffer in some degreeo h b ere ?re all plants in a felonious manner b w ~~i ~~s obtain their nectar corolla . and many . y . .nb holes through the ' c species, It might b th thu,s be exterminated. But her e . ought, would throughoht nature, there is at d e, as Is so general equilibrium If 1 · en eD:cytowards a restored . . . a pant suffers from b . f' . fewer Individuals will b . ; d ~In? per orat~cl, h . hl . . . e reare and If Its t . Ig y Important to the bees h' . . nee ar .Is suffer and decrease in number'· t b ese .In t~eu turn will effective as ' ut, what Is much more ' soon as the plant b rare so as not to g. . ecomes ·somewhat row In crowded h will no longer be stimulated to masses, t ~ bees flowers, but will enter them i gn~~ holes In the More seed will then be . d n ad legitimate manner. b . pro uce ' anu the u· mng the product of cross-fertilisation will b s~ec ~ngs so that the species will te d t . . . . e vigoious, b . n o Increase In number to e again checked' as soon as the plant ao·ain g . , ' . crowd~d masses. b rows 1n |