CONTENTS 



Page 



2. Normal and Experimental Pol- 



lination (Continued). 

 Pentstemon glaucus (Cont.). 



Middle lobe of the lower lip 



removed 77 



Upper lip removed 77 



Pentstemon secundiflorus 77 



Normal pollination 77 



Behavior 77 



Calendar 77 



Experiments 77 



Odor 77 



Powders and extracts 77 



Cotton wads sprinkled with 



peppermint 78 



Summary 78 



Monarda fistulosa 79 



Normal pollination 79 



Habit and structure 79 



Behavior 79 



Experiments 80 



Mutilation and competition. . . 80 



Plan 80 



Summary 88 



Resume 89 



Variation in number of visits. ... 89 



Changes of position 90 



Masking with cotton 90 



Mutilation 91 



Artificial flowers 92 



Painted flowers 92 



Honey and odor 93 



3. Competition and Constancy 94 



Significance 94 



Competition 94 



General plan 94 



Rubus strigosus 95 



General relations 95 



Rubus strigosus and Rubus deliciosus 95 



Comparison 95 



Experiments 95 



Summary 97 



Rubus strigosus and Rubus deliciosus 97 



Comparison 99 



Summary 99 



Competition of Rubus with Frasera, 



Cleome, etc 99 



Comparison 97 



Experiments 99 



Summary 99 



Rubus strigosus and two or more 



competitors 99 



Comparison 99 



Summary 100 



Rubus deliciosus 101 



Experiments 101 



Summary 101 



Rosa acicularis 101 



Comparison 101 



Experiments 102 



Summary 102 



Competition with normal and 



mutilated Aquilegia 105 



Geranium 105 



Comparison 105 



Experiments 106 



Summary 109 



Page 



3. Competition and Constancy (Con- 



tinued) . 



Chamaenerium angustifolium 110 



Comparison HO 



Experiments HO 



Summary HO 



Pentstemon HO 



Comparison HO 



Experiments 113 



Summary 113 



Monarda fistulosa 115 



Comparison H5 



Experiments 115 



Summary 115 



Weight and composition of pollen 



loads 119 



Value and methods 119 



Discussion 127 



Constancy 128 



Definitions 128 



Early observations of constancy 129 



Bennett's studies of constancy 130 

 Christy's studies of methodic 



habits 130 



Mueller's results 130 



Bulman's studies 131 



Ord's conclusions 131. 



Plateau and Perez 131 



Constancy in Bombus 132 



Lovell's conclusions 132 



Kranichfeld's observations 133 



Origin of oligotropism 133 



Resume 134 



Experimental results in compe- 

 tition 134 



Effects of competition 134 



Constancy as shown by pollen 



loads 135 



4. Principles and Conclusions 136 



Introductory 136 



Early experiments of Plateau and 



others 136 



Artificial flowers 136 



Nectaries 137 



Color sense of bees 138 



Response to detached petals. ... 139 

 Color preferences of nocturnal 



moths 140 



Response to color without anten- 

 nae '. 140 



Perception of form 140 



Response of wasps to color 143 



Response of wasps to odor 145 



Main researches of Plateau 145 



Masked flowers 145 



Removal of corolla 147 



Response to different colors 148 



Addition of honey to vivid nectar- 

 less flowers 149 



Anemophilous flowers 150 



Entomophilous flowers of dull 



color 150 



Artificial flowers, second series . . . 150 



Artificial flowers of green leaves . . 151 



Conclusions as to artificial flowers 152 



General summary 152 



Role of vexillary organs 153 



