298 



Mr. Dickie on Viviparous Plants, 



also possess the property of striking root when brought in 

 contact with the soil. 



In the other plants already mentioned, Polygonum vivipa- 

 rum and Saxifraga cernua, a very diflferent structure is pre- 

 sent. 



In Polygonum the perfect flowers are chiefly confined to the 

 apex of the stem ; beneath them are placed numerous oval 

 bodies of a purple colour, excepting near their summit, where 

 they have a different appearance, owing to the presence of a 

 thin loose membrane at that part. Each is supported by a 

 stalk, which is, however, so short as to be almost impercep- 

 tible. On making a longitudinal section, it will be seen that 

 each body consists of a strong membrane containing a gra- 

 nular substance. This last is principally cellular ; the cells 

 may be easily detached from each other, and each contains 

 numerous grains of starch. Imperfect spiral vessels pass 

 through the centre of the cellular substance. (Fig. 2.) The 



1 2 .5 4, 



purple membrane is itself covered by a cuticle, which is closely 

 adherent to it, excepting near the apex of each body, where it 

 becomes free, at which part also there is an arrangement ex- 

 actly resembling a bud 5 numerous scales are found, each in- 

 closing the other ; toward the centre they lose their membra- 

 nous appearance, are more succulent, and in the centre there 

 is a nucleus. (Fig. 1.) The cellular tissue in which the starch 

 occurs, when viewed in a mass, appears of a purple colour, 

 which is owing to the presence of numerous oblong cells that 

 have this tinge ; each separate starch cell is colourless, and 

 beautifully transparent. The imperfect spiral vessels already 

 mentioned pass from the point of attachment to the bud at 

 the apex. 



The small bulbous bodies occurring instead of flowers on 

 Saxifraga cernua, generally consist of two or more thick 



