en 



Xviii INTKODUCTIOfl. 



consideration, the real as well as the apparent number has now in most cases been 



agreed upon. 



131. The Flacenta is the part of the inside of the ovary to which the ovules are 

 attached, sometimes a mere point or line on the inner surface, often more or less thick- 

 ened or raised. Tlacentation is therefore the indication of the part of the ovary to 

 which the ovules are attached. 



132. Placentas are 

 axile, when the ovides are attached to the axis or centre, that is, in plurilocular 



ovaries, when they are attached to the inner angle of each cell; in unilocidar simple 

 ovaries, which have almost always an excentrical style or stigma, when the ovides are 

 attached to the side of tlie ovary nearest to the style ; in unilocular compound ovaries, 

 when the ovules are attached to a central protuberance, colunui,or axis rising up from 

 the base of the cavity. If tliis colunm docs not reach the top of the cavity, the pla- 

 centa is said to he free and central, 



. parietal^ when the ovules are attached to the inner surface of tlie cavity of a one- 

 celled compound ovary. Parietal placentas are usually shghtly thickened or raised 

 lines, sometimes broad surfaces nearly covering the inner surface of the cavity, some 

 times projecting far into the cavity, and constituting partial dissepiments, or evei 

 meeting in the centre, but without cohering there. In the latter case the distinction 

 between the one-celled and the several- celled ovary sometimes almost disappears. 



133. Each Ovule (121), when fidly formed, usually consists of a central mass or 

 nucleus enclosed in two bag-like coats, the outer one called primhie^ the inner one 

 seeitndhte. The cJialaza is the point of the ovule at which the base of the nucleus is 

 confluent with the coats. The foramen Is a minute aperture in the coats over the 

 apex of the nucleus. 

 131. Ovules are 



orihotropon,<t or straiglit, when the chalaza coincides with the base (36) of the 

 ovuloj and the foramen is at the opposite extremity, the axis of the ovule being straight. 

 campylotropous or incurved^ when the chalaza still coinciding with the base of 

 the ovule, the axis of the ovide is cnrvedj bringing the foramen down more or less to- 

 wards rthat base. 



anatropous or invei'ted^ when the chalaza is at the apex of the ovule, and the 

 foramen next to its base, the axis remaining straight. In this, one of the most frequent 

 forms of the ovule, the chalaza is connected with the base by a cord, called the raphe, 

 adhering to one side of the ovule, and becoming more or less incorporated with its 

 coats, as the ovule enlarges into a seed. • 



ampJiUj'opons or halfinverted^ wdien the ovule being as it were attached laterallVj 

 the chalaza and foramen at opposite ends of its straight or curved axis are about equally 

 distant from the base or point of attachment. 



§ 12. The Receptacle and Relative Attachment of tJie Floral Whorls. 



l^o. The Receptacle or torus is the extremity of the peduncle (above the calyx), 

 upon which the coroUa, stamens, and ovary are inserted. It ia sometimes Httle more 

 than a mere point or minute hemisphere, but it is often also more or less elongated, 

 thickened, or otherwise enlarged. It must not be confounded with the receptacle of 

 inflorescence (74). 



• 136. A Disk^ or disc, is a cu-cular enlargement of the receptacle, usually in the form 

 of a cup {cupular), of a flat disk or quoit, or of a cusluon {puhhiate). It is either 

 nimuxliately at the base of the ovary within the stamens, or between the petals and 

 Btamons, or bears the petals or stamens or botii on its margin, or is quite at the ex- 

 tremity of the receptacle, with the ovaries arranged in a ring round it or under it. 



137. The disk naay be entire, or toothed, or lobed, or divided into a number of parts, 

 usually equal to or twice that of the stamens or carpels. When the parts of the di^k 

 are quite separate and short, they are often called glands. 



13S. Nectaries, are either the disk, or small deformed petals or abortive stamefiSj 

 or appendages at the base of petals or stamens, or any small bodies within the flower 

 which do not loot hke petals, stamens, or ovaries. They were formerly supposed to 



