CH. VIIl] DEOSERA. 191 



be recorded by means of the graduations. The first 

 reading must be taken when the leaf is in its normal 

 position, the bottle being held so that the leaflet is 

 horizontal. The bottle is now turned over so that the 

 leaflet is still horizontal but upside down, and a second 

 reading is taken. If the pulvinus were absolutely rigid 

 the first and second readings would coincide; as it is 

 they differ by 5° — 15°. The leaf being replaced in the 

 first position, the pulvinus must be irritated by rubbing it 

 on the lower surface, or by a blow or two on the leaflet. 

 After one or two minutes have elapsed to give time for 

 the leaflet to sink, the above process of reading — revers- 

 ing — and reading a,gain must be gone through, when the 

 angular movement will be considerably increased, and 

 may be even double what it was before stimulation. The 

 same specimen should be used to measure the rigidity of 

 the leaflet in the nocturnal position. It will be found 

 that the excursion is very much smaller at night, — some- 

 thing like J of what it is in the day. 



(239) Brosera: stimulated by meat. 



The readiest way to observe the general character of 

 the movement of the tentacles is to place a very minute 

 fragment of raw meat on the gland of one of the outer 

 ones; this usually causes strong inflection in 7 or 8 

 minutes, by which the meat is after a time carried to the 

 centre of the leaf The gland should be carefully watched 

 under a lens in order that the time may be noted which 

 elapses between stimulation and the beginning of the 

 movement. An active leaf ought to show distinct move- 



