CH. VIll] MIMULUS. 195 



the induced current they may be made to close simul- 

 taneously: we simply wrap one wire round a small twig 

 of Berberis and touch the stigmas with the other wire. 



(243) Berberis: effect of chloroform. 



Gather a flower carefully with a pair of forceps, test 

 its irritability by touching a single filament and place it 

 floating in a watch-glass of water. Add a couple more 

 flowers similarly treated and place the watch-glass under 

 a bell (800 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'. 



(244) Stigma of Mimulus cardinalis. 



The stigma has the form of a pair of divergent lamellae 

 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- 



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

 Physiologische Vntersuchungen, 1873, p. 64. 



13—2 



