STRUCTURE AND FORMS OF THE OVULE. 



35 



carpels; in tlie other, falsely twice as many 

 of each, but the number of rows of ovules 

 should be the same in either case. In the 

 miutard and its relatives the false wall 

 connects the two ventral instead of the 

 dorsal sutures. While the lower portions 

 of the carpels are acting thus to form the 



ovary it must not be forgotten that the 

 upper portions are also uniting to form the 

 styles and stigmas, or stigmas alone, as 

 the case may be. Should the edges re- 

 main everted along more or less of the 

 style, they may fail to produce an epider- 

 mal covering and become stigmatic, giv- 

 ing us a marginal style. Should they be 

 Involute like the ovarian portions, the 

 stigma will be confined to the apex of the 

 style. In the syncarpous form there will 

 merely be a multiplication of these effects. 



develop a condition in which the dissepi- 

 ments are wanting the placentae will be 

 left unsupported in the axis (Fig. 201), 

 and will then be known collectively as a 

 Free Central Placenta. By progressive 

 abortion of the upper i>ortion this pla- 

 centa may become reduced to a trace at 

 the base. Upon the other hand, such a 

 placenta may become enlarged and 

 fleshy. Similar changes may occur in 

 the parietal placenta- It may become 

 reduced to a mere point preserved at the 

 apex, base or intermediate portion. In 

 the watermelon it becomes enormously 

 enlarged, filling the entire cavity with a 

 fleshy mass (edible). In the Obolaria 



(Fig. 202) it is laterally expanded to form 

 a more or less complete false lining to the 



ovarian cavity. In this position it may 



Quite a different group of appearances remain free or become coherent, so that 



will result from the higher or more com- 

 plex form of carpel union, by which the 

 proximate margins of two adjacent car- 

 pels meet and unite (Fig. 199) instead of 

 two belonging to the same carpel. The re- 

 sult of this form must be a single cavity or 

 a one-ceiled ovary, unless, as in the Mus- 

 tard (Fig. 200) one or more false septa 

 may divide it. Here, as before, however, 

 it is observed that the ventral portions of 



the entire face of the ovary may appear 

 to be ovuliferous. In other cases it actu- 

 ally is the entire inner face of the carpel, 

 which becomes the placenta. By a sub- 

 sequent obliteration of a portion of such 

 an expanded placenta the remaining 



portion may be seen to assume an ab- 

 normal position, being occasionally con- 

 fined to the midrib itself. 

 As has already been pointed out, the 



the carpels are directed toward the centre .number of ovules is extremely variable 



of the flower, the dorsal facing outward. 

 This law is invariable, no matter what the 

 number of the carpels or the form of ' 

 union. 



It will be observed that in ail cases in 

 which the margins of the same carpel 

 unite with one another, the placentae 

 will be formed at the centre or axis of the 

 flower. Such placentae are therefore 

 called Axile or Axillary (Figs. 198 and 

 201). Where the margins of different car- 

 pels unite (Fig, 199) the placentae must be 

 formed upon the walls or parietes, and 

 are therefore called Parietal. Such 

 placentae may by an extensive involu- 

 tion of the margins be carried very nearly, 

 or quite, to the axis (Fig. 286), but unless 

 cohesion actually occurs at that point 

 they are still parietal and the ovary is 

 one-celled. Some further modifications of 

 the placenta, either in itself or resulting 

 from modifications in the dissepiments, 

 must be carefully considered. If such a 



and the proportion of them which ^ be- 

 come fertilized is little less so. 



The position of the ovules is to a great 

 extent determined by the nature of the 

 placenta, as has already been explained. 

 It calls for a number of distinctive terms. 

 The two rows of ovules produced by the 

 two carpellary margins do not always 

 appear distinct, but may be reduced, be- 

 fore or after fertilization, to one. A ver- 

 tical row of ovules is called a series, and 

 ovules are thus defined as being One- 

 serialled, Two-serialled (Fig. 194), etc 

 When there are many series, so that the 

 number is not readily made out, we sim- 

 ply say that they are Many-serialled (Fig. 

 202). Ovules placed side by side (Fig. 

 194), are called Coliateral, Sometimes 

 no definite series can be made out, owing 

 to the crowding of many ovules into 

 small space, as in Obolaria (Fig. 202). 

 They are then said to be Crowded. Col- 

 lateral ovules, and, indeed, any ovules 



pistil as that represented in Fig. 198 shall standing together and deviating from 



