138 MOEPHOLOGY, OE COMPAEATITE ANATOMY. 



The coats of the ovule are usually regarded as foliar in their nature, the 

 nucleus as axial by others as a " trichoine " or superficial emergence 

 from the foliar coat of the ovule. The nucleus may be regarded as the 

 equivalent of a niacrosporangium among higher Cryptogams. 



The above is a description of the ovule of what may be called the normal 

 form, such as we find in Polygonum, &c. : where the nucleus is straight 

 and the micropyle is at the end opposite the attachment of the funiculus, 

 and the chalaza next the placenta, such an ovule is called straight, or, more 

 technically, atropous or orthotropous (fig. 268). 



Inversion and Curvation of the Ovules. Very frequently the 

 funiculus grows in a state of confluence with the outer integu- 

 ment, during the development of the ovule, so as to push up the 

 base of the nucleus until it is completely inverted (fig. 269), and 



Fig. 269. Fig. 270. 



c 



- WVS^t 



Diagrammatic vertical sections of ovules : a, the nucleus; b, the micropyle; c, chalaza; 



d, raphe. 



Fig. 268. An atropous or orthotropous ovule. 

 Pig. 269. An anatropous ovule. Fig. 270. A campylotropous ovule. 



the micropyle (b) points to the placenta, while the chalaza (c) is at 

 the opposite end, the nucleus being straight as in orthotropous 

 ovules : this is the inverted or anatropous condition ( Composite, 

 Liliaceae, &c.) ; and as the funiculus is confluent with the outer 

 coat, the hilum (the external point of junction of the funiculus with 

 the body of the ovule) is left in its original position, and therefore 

 close beside the inverted micropyle. The adherent portion of the 

 funiculus often forms a kind of ridge extending from the hilum to 

 the chalaza : this is termed the raphe (fig. 269, d). Other ovules 

 become anatropous not by reflexion, but by unequal growth. 



The inverted ovule is a straight ovule with a long funiculus confluent 

 with the outer coat: in Fumana (Cistacese) the real condition often 

 actually illustrates this ; and in seeds formed from anatropous ovules the 

 raphe sometimes separates {Zygophyllum, Willdenovia). 



The position of the raphe with reference to the ovule varies in different 

 cases ; sometimes it is ventral, or on the side of the ovule nearest to the 

 placenta, sometimes dorsal, at other times lateral. 



A curved or campylotropous ovule (fig. 270) is formed by the 



