STRUCTURE OF SEED. 203 



embryos which have no apparent cotyledons, as the 

 Dodder, these parts are confounded. 



The existence of the cauliculus has often been denied, 

 because this organ is sometimes so short, as to be scarcely 

 distinguishable ; but as the cotyledons always spring 

 from the stem, the great or small distance from their 

 point of origin to the neck, can always be perceived. 

 This length of the cauliculus also appears to be of little 

 importance in the symmetry of the young plant ; thus, in 

 the Papillionaceae, the French-bean presents it nearly 

 two inches long, and in the Pea, it is so short as to be 

 hardly visible. Its length influences, at the period of 

 germination, the situation of the cotyledons — whether 

 they be elevated above ground, or on a level with the 

 surface or subterranean ; these three manners are met 

 with in the Leguminosae, and the example is of itself 

 sufficient, independently of all other reasoning, to prove 

 that we cannot derive the primary divisions of plants 

 from these characters, as Willdenow has proposed. The 

 cauliculus is always simple, even in plants which become 

 the most branched ; almost always devoid of leaves, even 

 when they are very numerous near the root ; the branches 

 and leaves only begin to be developed above the cotyle- 

 dons. I only know one exception to these rules — 

 Euphorbia, which has sometimes buds upon the cauli- 

 culus below the cotyledons. 



The existence of the cauliculus, which is so evident 

 at germination, tends to prove that we ought not, as 

 some naturalists have done, to confound the neck, pro- 

 perly so called, i. e. the plane of separation between 

 the root and stem, with the point of origin of the coty- 

 ledons. These two points in the French bean are 

 nearly two inches apart, and never exactly coincide. 



The gemmule, or the part of the stem which is ele- 

 vated above the cotyledons, is truly the first bud of the 



