SIR J. LrEBOCK — PnXTOBIOLOGICAIi OBSERYATTO^'S. 393 



If these suggestions be correct, we should expect that species 

 with non- emerging cotyledons would generally have large seeds 

 and be aperispermic. This certainly appears to be the rule; 

 among the i^peeies with reference to whieli I have notes, there 

 are 37 genera in which the cotyledons are subterranean or remain 

 in tbe seed. The seeds themselves are notably large, and all but 

 three are aperispermic. Occasionally we meet with subterranean 

 and foliaceous cotyledons in the same genus, as, for instance, 

 in Rhus^ Mhamnns^ Mercurial is ^^ Pliaseoliis, &c. 



PJiaseoIus vuhjaris presents us with an intermediate stage, the 

 cotyledons being aerial and green, but fle^-hy and by no means 

 true leaves. In Mtlittis meliasopliijUiim^ ^g^iii? according to 

 Irmischt, the fleshy cotyledons generally remain in the seed, and 

 are lield together by the testa; but they sometimes burst the 

 shell, and stand out from one another. Like true subterranean 

 cotvledons, they have no stomata. 



AVlien the cotyledons are large, thick, and fleshy they often 

 contain sufficient nourishment to render the plants for some time 

 independent of any fresh sui)ply. In such cases the seedlings 

 sometimes push up for awhile without any fully-developed leaves, 

 the first few being reduced to very small size or almost obsolete, 



44) 



Size of E miry 0* 



As already mentioned, there are many cases, in fact many 

 whole orders, in which tlie ripe seed is entirely occupied by the 

 embryo; in other cases, again, as in I)eIj)Ji in i urn {hg. 130), the 

 embryo is very small, and examples of every intermediate stage 



might be given. 



Where it is an advantage to the plant that germination should 

 be rapid, this of course can be more readily secured if the embryo 

 is large. In fact, we find tliat species with large embryos, such, 

 for instance as Cabbage, Pea, &c., germinate much more rapidly 

 than those, such as Umbellifers, llauunculacese, &c., in which the 



embryos are small. 



On the other hand, in otlier cases, time is less important, and 



* Winkler, * Flora/ 1880, p. 3.39. 



t "Zur Naturge^chichte von MelitHs vxelh^ophjllum^'' Bot. Zeit. 1858, p. 233. 



