254 MOVEMENT IN PLANTS. 



the tube ; this is due to the contraction of the filaments pulling 

 down the anther tube. 



(6) Poke a mounted needle into the corolla-tube of a similar 

 flower, and note that the anther- tube is not merely pulled down, but 

 turns towards the side on which the stimulus has been applied to 

 the filaments. 



(c) Dissect out a number of similar flowers, and put them on 

 pieces of wet blotting-paper ; carefully slit down the corolla-tube in 

 each case and open it out so that the filaments may be seen. Invert 

 a tumbler over the flowers, and leave them for ten or fifteen minutes 

 to recover. In the rest position each filament is curved with the 

 convex side outwards. Touch a filament with the needle, and note 

 that it contracts and becomes straightened. As in Barberry, there 

 is no transmission of the stimulus from one filament to the next. 



359. Stigma of Mimulus. Examine the flower of 

 Mimulus, and note that the stigma consists of two diverg- 

 ing flat lobes, which on being irritated on the inner surface 

 close up. 



(a) Use the commonly cultivated Mimulus cardinalis for experi- 

 ments. Note that (1) in the unopened flower bud the stigma lobes 

 are pressed together ; that (2) the anthers of the two longer stamens 

 dehisce first, before the flower opens ; that (3) when the corolla 

 expands the two shorter stamens open ; that (4) then the stigma 

 lobes begin to diverge, and in three or four hours show a divergence 

 of about 90 ; that (5) after five to six days, during which the 

 irritability of the stigmas diminishes, they become spirally rolled 

 up (the inner surface remaining convex), and then wither ; and that 



(6) although the lobes are irritable as soon as the flower opens, the 

 stigma lobes do not close completely on being stimulated, only 

 reaching their complete irritability after about six hours ; and that 



(7) the lobes have completely lost their irritability after about six 

 days. 



(b) Touch the inner surface of one of the lobes with a pencil or 

 needle, and note that the closing occurs at once ; after five to eight 

 minutes they begin to diverge, and in ten to fifteen minutes have 

 reached their original position. Note that the outer surface of the 

 lobes is quite insensitive ; at any rate, no closure takes place when 

 they are stimulated. 



(c) Ascertain whether or not the stimulus is transmitted from one 

 lobe to the other. ; if so, we should expect that if one lobe is pre- 

 vented from moving, a stimulus applied to it would cause movement 

 of the other lobe. Cement, in one flower, the upper lobe, and in 

 another flower the lower lobe, to the corolla, by means of seccotine 

 (or of mastic dissolved in ether), and note that the stimulus is 

 transmitted from the fixed lobe to the free lobe in both cases, 



