444 MORPHOLOGY. 



with very different things, e. g. processes from the micropyle. The 

 formations of the aril are very various, and differ especially in 

 regard to colour, texture, and cell- contents. 



All the conditions here mentioned have already been explained in 

 previous sections ; here it suffices to notice them again in connection. 



180. The most important part of the whole fruit, as regards 

 the economy of the plant, is the seed (semen), because it encloses 

 the embryo, which is destined to perpetuate the species. The seed 

 may be quite free, without a pericarp, as in the Cycadacece, Coniferce, 

 and Loranthacece. Here the seed assumes quite the appearance of 

 a fruit ; for instance, of a winged achaenium in the Abietinece, of a 

 berry in Viscum, and of a drupe in Cycas, &c. 



In the seed two parts are to be distinguished, the episperm and 

 the nucleus ; the nucleus is either formed solely by the embryo, or 

 by that and the albumen. Then, again, the regions of the seed are 

 distinguished as the base, the part by which it is attached, and the 

 apex, the free point opposite to the former. The position of the 

 seed in the fruit is determined according to the relations of these 

 parts. The fruit is supposed to be erect, its base downward, and 

 the seed, of which the point stands higher than the base, is termed 

 erect, when it is attached at the bottom of the cavity of the fruit ; 

 ascending, when it arises from the lateral wall. Seeds of which the 

 apex is lower than the base are termed suspended or pendulous; if 

 the apex and the base lie on the same level, the seeds are termed 

 horizontal, or 'sometimes indeterminate (vaga). When the line from 

 the base of the seed to the apex forms not the longest but the 

 shortest diameter of the seed, it is styled peltate, or media affixa. 

 In the loose seed, that surface by which it was connected with the 

 funiculus is termed the hilum or umbilicus. 



All these terms would be rendered quite superfluous by the adoption of 

 a better method, since the position of the seed follows from the position 

 of the seed-bud ; but as the generality of our present books do not enter 

 into the structure of the seed-buds in the description of families, much 

 less in the characterisation of particular species, the preceding remarks 

 were required for the comprehension of our existing literature. 



The episperm, as explained above, allows no general reference to 

 the coats of the seed-bud, and, therefore, we can only speak gene- 

 rally of one episperm, and we must characterise the individual cell- 

 layers (strata) more minutely when the history of the development 

 of the particular species, genus, or family is still unknown. The 

 epidermis of the seed may be almost universally distinguished from 

 the episperm with advantage. On its surface are described hairs 

 (issuing from the micropyle in a tuft), as coma, papillae, prickles, 

 ribs, wings, &c., and the regions of the raphe, of the chalaza, arid 

 of the micropyle. 



The old school doctrine, here quite wrong, says that the coat of the seed 

 consists of two membranes, the proper coat of the seed (testa, lorica, 



