SIR J. LUBBOCK — PHYTOBTOLOGICAL OBSERVATIONS. 



370 



clear that the lobes are due to the manner In which the emhryo 

 is folded. 



In (Enolhera and some allied species the cotyledons also 

 present a terminal lobe. This, however, is not due to folding. 

 The terminal lobe is the original cotyledon, and the basal portion 

 is altogether subsequent growth, which moreover, to some extent, 

 assumes the character of the true leaf. I shall refer to this in- 

 teresting group in more detail on a subsequent occasion. 



The case of Fetiveria octandra (fig. 81) has been already 



described. 



Emarginate Cotyledons* 



In a great many species the cotyledons are emarginate, or even 

 more or le^^s deeply bifid. No explanation of this has, so far as I 

 know, yet been offered. It is, in fact, as I shall hope to show, by 

 no means always due to the same cause. 



One of the simplest cases is that of the Oak, where the thick 

 fleshy embryo occupies the whole of the seed. The chalaza is 

 'situated at the centre of one end, at the extremity of the cotyle- 

 dons, and the w^alls of the seed being at tliat point somewhat 

 thickened, the cotyledons are slightly pressed in. The same ex- 

 planation applies to various other species, as for instance to the 

 Impatiens (figs. 12 and OS), Potenum (figs, 42 and 90), Cu^hca 

 (fig. 100), and Nettle {Tlrtica, fig. 101), 



Fig. 98 



(fh 



Fig. 99. 



Fig. 98. 



Longitudinal and transverse sections of seed of Impaficm parvtjlora. 

 X 10. P/, Plumule. 

 Fig. 99. Longitudinal section of Poferium SanguUarha, X 0. ct, calyx-tubo; 



a, acbene ; rf, rcceptacioT 



