208 M. MIYOSHI. 



repeated several times in a given flower apparently without any 

 sign of decrease in irritability. The experiments may also be made 

 on the plants kept in the house with just as good results as on those 

 in their natural habitats. Of the flowers detached from the shoot, 

 the same holds good as long as they are prevented fi-om withering. 



*The stigmatic lobes, when magnified are seen to be made up of 

 bundles of filaments (^Pl. XXIX, Fig. 10, 11, loos, tiss.) composed oi 

 cells full of granular protoplasm. The filaments are very loosely 

 acro-regated, passing below to the closer conducting tissue (cond. tiss.) 

 of the style. The inner sui-face (Tig. 10) of the lobe is quite naked 

 but studded with many papillœ (pap.) or the clavate apices (clav. ap.) 

 of the above-mentioned filaments, among which the pollen-grains (pol. 

 gr.) take lodgement. The outer surface (Fig. 11), on the contrary, 

 is loosely covered with a very thin layer of epidermis (directly con- 

 tinuous with that of the style), the cell-walls of which are more or 

 less cuticularized and marked with minute longitudinal wrinkles 

 (Fig. 11). Besides, there may be seen differences in the outlines of 

 the component cells of the epidermis, as we pass from the lobes of 

 the stigma (stig.) to the stylar portion (styl.) below — those of the 

 former being irregular and sinuate, while those of the latter are almost 

 rectangular. 



As has been pointed out by Pfeffer. Sachs, and others, cells form- 

 ino" irritable parts of plants, when acted on by external stimulus, 

 allow water to pass out of their protoplasm, thereby suffering 

 diminution of volume ; and this contraction affecting the exten- 

 sive and elastic cell-walls makes the motion visible to the naked eye. 

 This, I believe, may also explain the irritability in the present case, 



* The sfcruetares o£ the style and stigma have been studied by J. Behrens. (Untersuchungen 

 über den anatomischen Bau des Griffels und der Xarben. Göttiugen, 1875 ) 



