on the green parts of Hibiscus vitifolius Linn. 205 



tissue lying between. A similar behaviour occurs in Bombax 

 erianthos. 



In some cases single cells divide, but usually they only swell. 

 In Chorisia asperifolia and Quararibea jloribunda the whole 

 surface of the epidermis does not swell regularly, but parts of it 

 rise up " island-like " and specially strongly. 



As Kuntze does not figure any cases of swollen epidermis it 

 is difficult to compare the appearances he describes with those 

 which occur in Hibiscus vitifolius, or to determine whether there 

 is any relation between them. 



Evidently the author regards the occurrence he describes as 

 normal and not pathological, and, as far as it is possible to judge 

 from a description, the swellings he notes are different from those 

 in Hibiscus vitifolius. Certainly the outgrowths in Hibiscus 

 vitifolius are not an aqueous tissue as was shewn by the ex- 

 periment recorded above (p. 14). 



But the fact that the epidermis, not only in the same family, 

 but in the same genus, is capable of swelling, apparently as 

 a normal process, is in itself interesting and suggestive when 

 considered in connection with the outgrowths in Hibiscus viti- 

 folius. It seems not impossible that, under glass, the develop- 

 ment of some powerfully osmotic substance may be favoured, 

 which is not formed in the open. No such body has however 

 been detected in the cells, and the matter needs further investi- 

 gation. 



Kuntze does not say under what conditions the swelling of the 

 epidermis takes place, so that again it is impossible to compare 

 the phenomena he describes with those in H. vitifolius. 



It may here be noted that Haberlandt 1 describes certain plants 

 in which the stomata are normally raised above the level of the 

 epidermis. In some cases the lifting up is scarcely noticeable, but 

 in others, as, for example, in the peduncle of Gucurbita Pepo, it is 

 so strongly marked that the stoma is placed at the apex of a 

 spherical or cylindrical papilla whose lumen is continuous with the 

 respiratory cavity. The biological importance of this position of 

 the stomata is uncertain. From the circumstance that raised 

 stomata not infrequently occur in plants which grow in damp and 

 shady situations, as for example in different ferns, it may in 

 Haberlandt's opinion be inferred that the exposed position of the 

 stomata may be a means of promoting transpiration. 



Outgrowths, comparable to those of Hibiscus, but quite 

 definitely pathological, and differing considerably in structure, 

 have been described by several authors, on different plants. 

 Amongst these may be mentioned the following : — 



1 Haberlandt, Physiologische Pflanzenanatomie, 1896, p. 406. 

 VOL. X. PT. IV. 15 



