416 THE GARDENER. [Sept. 



Bean or Pea when the skin is taken off presents a good example of 

 nothing but the embryo. The embryo of the seed of a Palm when cut 

 vertically is very small and white. The seed may also be described as 

 the ovule {see No. VII.) arrived at maturity, and consists of integuments, 

 — collectively termed testa, which consist of membranes resulting from 

 the sacs of the ovule, and sometimes expanded into wings, that are 

 probably intended to render seeds buoyant, and are frequently spongy, 

 and sometimes consist of spiral cells, — and embryo — which is the 

 organised body that lies within the seed, for the purpose of protecting 

 and nourishing which the seed was created — and was originally included 

 within the sac of the amnios which contains a fluid in which the 

 embryo is developed, and which is usually absorbed or obliterated 

 during the advances of the embryo to maturity ; being exceptional in 

 the case of Vitellus, &c., where it remains surrounding the ripe embryo. 



The embryo consists of (1) cotyledons, (2) radicle, (3) plumule, and 

 (4) collar. The cotyledons represent undeveloped leaves, — a very good 

 example is found in the Broad Bean, whose cotyledons, after perform- 

 ing the required functions under the soil, are afterwards formed into 

 the first leaves or cotyledon leaves. The radicle is (the rudiment of) 

 the descending axis or root, which throws out fibrils and spongioles, to 

 absorb moisture and other nourishment, and to preserve the plant's 

 equilibrium. The plumule is the ascending axis, which gives out the 

 stems, leaves, flowers, &c. The collar is the line of separation between 

 the radicle and the cotyledons, and the space between the collar and 

 base of the cotyledons is called cauliculus. 



The direction of the embryo, with respect to the seed, will depend 

 upon the relation that the integuments, (l) the raj^he {i.e., the cord of 

 fibro-vascular tissue which connects the base of the nucleus of an ovule 

 with a placenta); (2) the chalaza (the part of the seed where the 

 nucleus joins the integuments, and is invariably opposite the end of 

 the cotyledons) ; (3) the hilum ; and (4) the micropyle (the aperture 

 in the skin of a seed which was once the foramen of the ovule) — 

 bear to each other. If the nucleus be erect, the embryo will be in- 

 verted, or antitropal : Ex. Nettle. If the nucleus be inverted, the 

 embryo will be erect, or orthotropal : Ex. Apple. If the micropyle is 

 at neither end of the seed, the embryo will be neither erect nor 

 inverted, but will be in a more or less oblique direction with respect 

 to the seed ; and it is said to be heterotropal : Ex. Primrose. 



These must not be confounded with similar terms applied to the 

 ovule, and consequently to the seed itself. In general seeds are, like 

 ovules, enclosed within a covering, arising from a carpellary leaf ; but 

 all gymnosperms are an exception to this. Moreover, some ovules rup- 

 ture the ovary soon after they begin to advance towards the state of 

 the seed, and thus become naked seeds : Ex. Leontics. Others are 

 imperfectly protected by the ovary, the carpels not being perfectly 

 closed up : Ex. Reseda. 



