( 135 ) 



aQ;ain Iioi-izoiitally expaiulod, tlic inidrih of each leaflet Iteiiig al li^^lit 

 angles with the secondary rachis. 



5 tehruai'ii. 8.45 p.m. — The plant is standing oiil ot' doors at 

 a sheltered place. No rain. No wind. Since abont 2 honrs there has been 

 a thnnderslorni. All the leaflets have taken the so characteristic noc- 

 tnnial position. The}- all have, namely, by night their tops directed 

 vertically downwards, the n|)per snrfaces of each i)air pressed 

 together, the leaflets on the same side of the secondary rachis being 

 imbricated. Hereby the midrib of the leaflets stands ^■ertically or 

 more or less inclined on the secondary petiole, the latter being placed 

 with all its leaflets in a nearly vertical plane. A comparison of the 

 noctnrnal positioii of Poinciama i-e(]ia with that assumed within 3 

 minutes by the strongly irritated leaflets, proves that in the latter 

 case the movement amounts about to the half of that performed in 

 from 1 — iVa hour at the passage from day to night position. 



7 Fehruiu'ii, 1 />. m. - Cloudy. No wind. — All the leaflets are 

 in non-irritated day position, quite expanded. x\bout 3 minutes after our 

 slightly tapping with a lead-[)encil on the leafstalk and the common 

 rachis of the topmost leaf, all the leaflets of the irritated leaf had 

 taken the before described "irritation position", apparently, however, 

 the irritation had not been ti'ansmitted to the other leaves. At least 

 after a quarter of an hour the latter did not yet show irritation 

 movements and all the leaflets were quite outspread whereas, still 

 then, all the leaflets of the irritated leaf were in the described highly 

 interesting "iriitation position". 



7 Febraanj, 4 p. m. — It has become dark since 7- hour. The 

 leaves are nearly in the nocturnal positio]i. Only in the topmost 

 leaves each pair of leaflets has its upper surfaces closely pressed 

 against each other. In the other somewhat older leaves the leaflets 

 are almost, but not closely, pressed together. It further aj)pears that 

 the closing of the leaflets takes place acropetally at the secondary 

 rachis. 



11 Fehniani. 2 p. in. The experiment plant in iion-irritaicd 

 condition (now with its leaves quite outspread) is cautiou.sly, without 

 shaking, placed in a shut cupboard. 



Idem, 4 p. m. — All the leaves have the peculiar appearance 

 of the "irj'itation (position", but not one shows the "nocturnal posi- 

 tion". This was neither the case at another date by day after the 

 plant had been left 5 hours in the dark room. In the latter case 

 also all the leaves had the pecidiar clog-wheel appearance, chai-ac- 

 teristic of the "initaliou jiosition", with obli(piely rising ["shape- 

 placed leaflets, whilst yet in not one leaf the downward turned 



