34 



ESSENTIALS OF VEGETABLE PHARMACOGNOSY. 



these indications to appear, the internal 

 structure must be studied. For this pur- 

 pose both longitudinal and transverse sec* 

 tions must be made. The former should 



r.5/82. 



F'g >ei- 



^S -^S-^ 



■JV/ /s/. 



r.g. >8^. 



Fiy IhS. 



?,g.i8S 



^g.iqfa. F(^ 191 



be so directed as to lay open the inside of a 



carpel, and of the latter there should be 

 three, through the lower, middle and up- 

 per portions respectively. In most cases a 

 good lens will be sufficieiit to present the 

 characters, but when insufiicient, recourse 

 must be had to the stage and low power of 



compound microscope. 



Although appendages to the pistil dur- 

 ing the flower-stage are less frequent and 

 less varied than in the case of the audroe- 

 cium^ yet none of the forms which we 

 hftve there observed are here excluded. 



Two distinct types of the carpel re- 

 spectively characterize the Gymnosperma 

 and the Angiosperms, both of which 

 classes contribute important medicinal 

 plants. The essential character of the 

 former is illustrated in Pig. 192. Thia 

 consists in its not being shaped into an en- 

 closure for containing the ovules. In this 



instance there is no progress toward such 

 a couditiou, the carpel remaining more or 

 less flat and bearing the ovules upon its 

 surface. In the progressive forms there 

 is a cavity formed, but it is never com- 

 pletely enclosed. A higher development of 

 it is found in the Taxus or Yew (Fig. 193). 

 The pseudo-cavity of the gymnospermoua 

 carpel is never divided. 



There are two modes of the enclosure of 

 the cavity of the monocarpellary angio- 

 spermous ovary. In the first (Fig. 194) 

 the margins of the carpel meet one an- 

 other, and then, by more or .ess of an invo- 

 lution, form the placenta (a), with its 

 two rows of ovules (b and c). By the 

 other mode (Figs. 195 and 196) the mar- 

 gins turn in and meet the midrib, form- 

 ing two cavities, each containing half of 

 the placenta with its one row of ovules. 

 The posterior portions of the carpels thus 

 brought into juxtaposition (a and b) 

 may unite (Fig. 19G) or remain distinct 

 (Fig. 195). In other cases where a sim- 

 ilar condition exists, it has resulted from 

 the outgrowth from the midrib, across a 

 cavity of the first form, of a false wall or 

 dissepiment, as in the flax (Fig. 197). The 

 placenta and ovules are then found upon 

 the ventral side. It is to be remembered 

 that these are then false cells, each two 

 being indicative of one carpel. With rare 

 exceptions the distinction is to be made by 

 observing the separation of the two rowfl 

 of ovules. If we imagine two, three or 

 more carpels, constructed in any of these 

 ways, standing face to face, and cohering 

 in this position, we have a perfect idea of 

 the simplest forms of the syncarpous pis- 



FLcr^aoa 



Ti^ ^Od: 



Fio ao3 



f to 200 



a. 



Ftcr- ^Ot>- 



(=L«J. 2.i>t. 



F,^ aofc- 



F^g ;2.o7 



til. In the one case (Fig, 198) we shall 

 have as many walls and cells as there are 



