APPENDIX II 



Read Kerne r and Oliver, Volume II, Part i, pp. 228, 

 260, 261, 267, 268; Gray, Text-book, pp. 184-189, 

 225-229 ; Allen, The Story of the Plants, pp. 90-98 ; 

 Lubbock, Flowers, Fruits, and Leaves, pp. 27-30. 



V. Orchids of various kinds may generally be obtained from 

 the greenhouses. The pollen masses may be demonstrated 

 and the method of their withdrawal. Certain native species, 

 especially of Habenaria, may often be obtained. The 

 material used should be alive and a pencil tip or a bristle 

 be employed to represent the proboscis of an insect. 



Read Kerne r and Oliver, Volume II, Part i, pp. 254-257, 

 269, 270; Gray, Text-book, pp. 230-234; Weed, Ten New 

 England Blossoms, pp. 72-89 ; also Darwin, On the Fer- 

 tilization of Orchids by Insects. 



Species of Milkweed (Asclepias) have pollinia, and living 

 material may be introduced into the laboratory whenever 

 possible and the process of pollination be demonstrated. 



Read Kerner and Oliver, Volume II, Part i, pp. 257-260 ; 

 Gray, Text-book, p. 233 (bottom). 



VI. The lack of symmetry is usually connected more or 

 less directly with irregularity and is brought about by the 

 suppression of parts of different circles. 



Read Gray, Text-book, pp. 187-190. 



CHAPTER XXI 



COALESCENCE AND ADNATION 



COALESCENCE and adnation are directly concerned in the 

 same way as irregularity, in devices to ensure insect pollina- 

 tion. They modify the structure of the flower so as to 

 exclude insects of no use for this purpose, and to cause the 



