THE ESSENTIAL ORGANS. 



coat, which is very thin and expansible, is uncovered. In the 

 fluid are suspended 

 molecules of incon- 

 ceivable minuteness, 

 said to possess a trem- 

 ulous motion. When 

 the membrane is ex- 

 posed to moisture, it 

 swells and bursts, 

 discharging its con- 

 tents. 



122. In the Orchids 

 and Silkweed tribe, 

 the pollen grains do 



not Separate as intO a ,, 2 Sectlonof thePassIon-flowerfPassifloraccenilea); b, bracts 

 rlnet r\v -r>/->iirrlov Vmt of the involucre; , sepals; p, petals; a, a, staminodia or neriU 

 1 pO\VU.ei, IHIL filaments; c, stipe; o, ovary; d, stamens; t, stigmag. 



all cohere into masses 



called POLLINIA, accompanied by a viscid fluid. 



Review. 110. Position of the stamens. 111. Members, compared with a leaf. Pollen. 

 The filament. 113. The anther. Connectile. Dehiscenoe. In 82, point ont these 

 parts. 114. How the anther is attached to the filament 3 modes. Of dehiscence 3 

 modes. Define "anther introrse" "Anther extrorse." What figures illustrate ? What 

 are dimidiate anthers? 115. The cells in regard to number. Mention some appendages. 

 What are staminodia? 118. Define the terms definite and indefinite, as applied to the 

 stamens. Define the terms relating to position To inequality in length. 120. Four 

 terms relating to cohesion. Three terms expressing absence. The pollen as seen under 

 the microscope. Structure. Pollinia. 



CHAPTER VIII. 



OF THE ESSENTIAL ORGANS. THE PISTILS. 



123. The Gyncocium occupies the centre of the flower, at 

 tho termination of the axis. It consists regularly of a circle of 

 distinct pistils (^ 60), symmetrical in number with the other 

 circles. It is subject to great variation. The pistil may oe dis- 

 tinct and simple^ as in Columbine, or coherent in various degrees 

 into a compound body, as in St. Johnswort. Also instead of 

 being free and superior, as it regularly should be, it may adhere 

 to the other circles, as already explained ( 97), and boconuj 



