CH. VIIl] MIMULUS. 211 



a bell (1000 c.c. capacity) with another watch-glass 

 containing 4 or 5 drops of chloroform. The flowers can 

 withstand 10 minutes of this atmosphere without suffering 

 and will be found quite insensible to touches. 



After half-an-hour's exposure to fresh air (and 

 possibly in a shorter time) they are found to be once more 

 irritable. 



It is interesting to repeat the experiment with flowers 

 in which the filaments have been irritated just before 

 they are put under the bell-jar. It will be seen that the 

 stamens recover the normal position in spite of the 

 anaesthetic 1 . 



(244) Stigma of Mimulus cardinalis. 



The stigma has the form of a pair of divergent lamellaB 

 which, when irritated, rapidly shut together so that one 

 stigmatic surface meets and presses against the other. 

 The inner surface is the sensitive part, a touch on the out- 

 side of the Iamella3 produces no effect. Oliver 2 has shown 

 that if one lamella is prevented from moving, a touch on 

 it still provokes movement in the other lamella. In our 

 experiments we fixed one lobe by cementing it to the 

 corolla, using mastic dissolved in ether for the purpose. 

 When the cement is dry it is well to push a strip of wood 

 between the style and the corolla : by a wedge of this 



1 The same thing is said to occur in the case of Mimosa : see Pfeffer, 

 Physiologische Untersuchungen, 1873, p. 64. 



2 Bericlite d. deutschen botan. Gesellsch. v. 1887, p. 167. Transmission 

 of stimulus has only been observed in Marty nia lutea, M. proboscidea 

 and Mimulus cardinalis. There is said to be no transmission in Mimulus 

 luteus. 



142 



