378 



SIB J. LUBEOCK PlIYTOBIOLOGICA-L OESERYATIOXS. 



Lastly, in cases where the cotyledons do not leave the seed, 

 the petioles leave room for the free growth of the plumule, as iu 

 Sapindtcs (fig, 43)« 



Loled Cotyledons, 



The great majority of cotyledons are entire, hnt some are more 

 or less lohed. Tor instance, tho$e of the Mallow (fig. 35) are 

 broadly ovate, minutely emarginate, cordate at the base, and 3- 

 lobed or angled towards the apex, with three veins, each running 

 into one of the lobes. 



Those of lUtvatera and Allhcea are similar. The embryo is 

 green, curved, and occupies a great part of the seed. The cotyle- 

 dons are applied face to fiice, tlien, as growth continues, the 

 tip becomes curved, and depressed into a mcdiiin longitudinal 

 furrow, the fold of the one lying in that of the other. 

 • The embryo is a small body of the form shown in fig. 05 : the 

 'horn or process r is the radicle; the rest is tlie cotyledon, ot 

 which the free end / is folded on itself and turned downwards. 

 In this way the embryo occupies the seed, leaving a small spjit-'^ 



between y 



a 



by perisperm. Perhaps it may nuihe the arrangement clearer 

 to take a piece of note-paper, cut it into the form of an e^^^^ 



Fig. 05. 



Fig. OG. 



Fiir. 97 



Fig. 95. Eiubrjo of Mallow. Enlarged. 



Figs. OG & 97. Piece of paper prepared to show the mode and effect of the 



folding of the embryo. 



(fig. 9G), turn the broad portion ab downwards, so that the 

 parts a and h have tbeir under faces turned to one another, and 

 then press down the line 



/, and bring the points c 



and d 



'f and d ef 



f 



We sliall then tave an 



object shaped as in tig. 97, witli a sliarp point at c, wliicli would 

 not conform to tlie rounded shape of the seed. IN no^r, to 

 make it do so, we cut off the point c along the dotted hne 

 and'then unfold the jiaper, we shall find that it has the form of 

 the cotyledon of Maha (fig. 35) wdth a bay or notch on each side. 

 In Erodium the arrangement ia somewhat similar, and it secnw 



