3G2 



SIR J. LUBBOCE — PHYTOBIOLOOICAL OBSERVATIOXS 



(figs. 49 and 50) is laterally compressed and horscsboe-sliaped, with 

 a crest along the edge; the seed (fig. 51) conforms to the shape 

 of the fruit, and the embryo is curved and linear, the cotyledons 

 being applied to one another face to face, and at right angles to 

 the plane of the seed, so that the edges of the cotyledons touch 

 the walls of the seed at each side. 



Fig. 49. 



Fig. 50. 



Fig. 51. 



Fig. 49. 



^lenisperTmcm canadense. 

 Germinating seedling, x 2. Fig. 50. Vertical section of seed, X 4, 



Fig. 51. Transverse section of seed, X 2. 



Fig. 52. 



A 



4£c?' P^etido-Plafanus. 

 Fruit, nat. size. A, B. Enibrjo, showing two modes of arrangement of 



cotyledons. 



The Sycamore (Acer Pseudo-Platanus, fig. 9) has also narrow 

 cotyledons ; but the arrangement is very different. The fruit 

 (fig. 52) is winged, the seed somewhat obovoid and aperispermic 

 that is to say, the embryo, instead of lying embedded in food- 

 material, occupies the whole cavity of the seed. Now if we 

 wished to pack a leaf into a cavity of this form, it would be found 

 convenient to choose one of a long strap-like shape, and then roll 

 it up into a sort of ball. This is, I believe, the reason why this 

 form of cotyledon is most suitable in the case of the Sycamore. 

 The mode of folding, however, as shown in fig. 52, A and B, is not 



