. irORPHOLOGY OF REPRODUCTIVE ORGANS 218 



observed (fig. 467, etid). The coat thus formed, where there is 

 but one, is called the integuinentum simplex, s ; and the orifice, 

 end, at the apex of the nucellus, n. is termed the micro2Jijh' or 

 foramen. There is only one coat formed in the Compositas, 

 Campanulacese, Lobeliaceae, and some other orders. 



In most plants, however, the ovule has two coats, in which 

 case we observe two cu'cular or annular processes around the 

 base of the nucellus, the inner one being first developed ; these 

 processes continue to grow upwards as before described, until 

 they also ultimately form two sheaths or coats, which entirely 

 enclose the nuceUus except at its apex (fig. 468). The inner 

 coat is at first seen to project beyond the outer, but the latter 

 ultimately reaches and encloses it. The inner coat is usually- 

 termed the secuntline (figs. 408, s, and 469, c), and the outer the 



FiGf. 46,5. 



Fig. 466. 



Fig. 467. 



Fig. Kiy. 



Fit/. 465. Ovule of tbe Slistletoe ( KiscHWl aZfrym), consisting of a naked 

 nucellus. Fiff. 4QG. The same ovule cut vertically to show the embryo- 

 sac, /', in the nucellus, ". Fief. 467. Ovule of the Walnut (Jiit/lar/s i-atfia). 



71, Projecting end of the nucellus. s. Coat covering the nucellus except 



at the foramen, end. Fig. 468. Ovule of a species of Folygonum. f. End 



of ovule where it is attached to the placenta, p. Primine. s. Secundine. 

 px. Exostome. nnh Endostome. n. Projecting end of the nucellus. 



primine ; but some botanists, following the order of development 

 of the coats, term the inner coat the primine, and the outer the 

 secundine, thus reversing the order of names as above mentioned. 

 Others, to prevent confusion, more properly term the inner coat, 

 or secundine, the integuinentum internum, ; and the outer coat, 

 or primine, the integumentum externum. The orifice left at 

 the apex of the nucellus, as in the former instance where only 

 one coat is present, is called the foramen or micropyle. The 

 openings in the two coats commonly correspond to each other, 

 but it is sometimes found convenient to distinguish them by 

 distinct names ; thus, that of the outer is called the exostovie 

 (fig. 468, ex) ; that of theioaer, endostome (end). 



The nucellus and its coat or coats are intimately connected 

 at one point, called the chaJaza (figs. 470, ch, and 471, cli) ; but 



