OF BOTANY. XXXI 



405. In such cases, a vascular connexion is maintained between the base of 

 the ovulum and the base of the nucleus, by means of a bundle of vessels called a 

 raphe. 



406. The normal position of this raphe is on the side of the ovulum, next the pla- 

 centa. 



407. The expansion of the raphe, where it communicates with the base of the 

 nucleus, gives rise to the part of the seed called the chalaza (491). 



408. The mouths of the primine and secundine usually contract into a small 

 aperture called the foramen of the ovulum, or the exostome. 



409. The apex of the nucleus is always applied to this foramen. 



410. In consequence of the ralation the base of the nucleus bears to the base of 

 the ovulum, the foramen will be at the apex of the ovulum when the two bases 

 correspond, and at the base of the ovulum when the two bases are diametrically op- 

 posite. 



411. It is through this foramen that the impregnating molecules of the pollen are 

 introduced into the nucleus (332). 



412. The foramen indicates the future position of the radicle of the embryo (492) ; 

 the radicle being always next the foramen. This is a fact of great importance in 

 practical Botany. 



413. From some recent observations, it appears that the nucleus consists of 

 three coats ; the outer called the tercine, the next the quart hie, and the most inte- 

 rior the quintine. 



414. But these are not always distinguishable, and part of them is usually ab- 

 sorbed during the advance of the ovulum to the state of a seed. 



415. The tercine and quartine are finally converted into albumen (494) ; the quin- 

 tine becomes the sac of the embryo (501), whenever that sac is distingishable ; Ex. 

 Nympham. 



416. The nucleus contains a pulpy mass called the liquor amnios, which is sup- 

 posed to be the substance from which the embryo absorbs its nutriment during its 

 growth. 



XVI. FRUIT. 



417. The Fruit, in the strictest sense of the word, is the pistillum arrived at 

 maturity. But the term is also applied to the pistillum and floral envelopes taken 

 together, when they are all united in one uniform mass. 



418. Hence, whatever is the structure of the pistillum, the same should be the 

 structure of the fruit. 



419. But in the course of the advance of the pistillum towards maturity, many al- 

 terations take place, in consequence of abortion, non-developement, obliteration, and 

 union of parts. 



420. Whenever the fruit contains any thing at variance with the laws that govern 

 the structure of the pistillum, the latter should be examined for the purpose of elu- 

 cidation. 



421. Sometimes a pistillum with several cells produced a fruit with but one ; 

 Ex. the Hazel-nut and Cocoa-nut. This arrises from the obliteration of part of the 

 cells. 



422. Or a pistillum, consisting of one or two cells, changes to a fruit having 

 several : the cause of this is a division and doubling of the placentary divisions ; 

 Ex. Martynia : or the expansion of portions of the placenta ; Ex. Cathartocarpus 

 Fistula. 



423. As the fruit is the maturation of the pistillum, it ought to indicate upon ils 

 surface some traces of a style : and this is true in all cases, except Cycadeae and 

 Conifers?, which have no ovarium. 



424. Hence the grains of corn, and many other bodies that resemble seeds, hav- 

 ing traces of the remains of a style, cannot be seeds, but are minute fruits. 



425. That part which was the ovarium in the pistillum becomes the pericarpium 

 in the fruit. 



426. The Pericarpium consists of three parts, the outer coating called the epi- 

 carp, the inner lining called the endocarp or putamen, and the intermediate sub- 

 stances named the sarcocarp. 



427. Sometimes these three parts are all readily distinguished ; Ex. the Peach , 

 frequently they form one uniform substance ; Ex. a Nut. 



428. The base of the fruit is the part where it is joined to the peduncle. The 

 apex is where the remains of the style are found. 



