G24 ASCLEPIADACE^E. [Perigynous Exogens. 



which afterwards occupy the angles of the stigma were absolutely invisible ; the furrows 

 of its angles were extremely slight, and, like the body of the stigma, green ; the autherae, 

 however, were distinctly formed, easily separable from the stigma, and their cells, which 

 were absolutely shut, were filled with a turbid fluid, the parts of which did not so cohere 

 as to separate in a mass ; of the cuculli, which in the expanded flower are so remarkable, 

 and constitute the essential character of the genus, there was no appearance. 



"In the next stage submitted to examination, where the corolla nearly equalled 

 the calyx in length, the gland-like bodies of the stigma were become visible, and con- 

 sisted of 2 nearly filiform, light-brown, parallel, contiguous, and membranaceous 

 substances, secreted by the sides of the furrow, which was now somewhat deeper. 

 Instead of the filiform processes, a gelatinous matter occupied an obliquely descending 

 depression proceeding from towards the base of each side of the angular furrow. 



" In a somewhat more advanced stage, the membranes which afterwards become 

 glands of the stigma were found to be linear, closely approximated, and to adhere at 

 their upper extremity. At the same time the gelatinous substance in the oblique 

 depression had acquired a nearly membranaceous texture and a light-brown colour ; 

 and on separating the glands from its furrow, which was then practicable, this mem- 

 brane followed it. At this period, too, the contents of each cell of the antherse had 

 acquired a certain degree of solidity, a determinate form, and were separable from the 

 cell in one mass; the cuculli were also observable, but still very small and green, nearly 

 scutelliform, having a central papilla, the rudiment of the future horn-like process. 

 Immediately previous to the bursting of the cells of the antherse, which takes place a 

 little before the expansion of the corolla, the cuculli are completely formed, and between 

 each, a pair of minute, light-green, fleshy teeth are observable, the single teeth of each 

 pair being divided from each other by the descending alee of the antherse. The glands 

 of the stigma have acquired a form between elliptical and rhomboidal, a cartilaginous 

 texture, and a brownish-black colour ; they are easily separable from the secreting fur- 

 row, and on their under surface there is no appearance of a suture, or any indication of 

 their having originally consisted of two distinct parts ; along with them separate also 

 the descending processes, which are compressed, membranous, and light-brown ; their 

 extremity, which is still unconnected, being more gelatinous, but not perceptibly thick- 

 ened. The pollen has acquired the yellow colour, and the degree of consistence which 

 it afterwards retains. On the bursting of the cells, the gelatinous extremity of each 

 descending process becomes firmly united with the upper attenuated end of the corre- 

 sponding mass of pollen. The parts are then in that condition hi which they have been 

 commonly examined, and are exhibited in the figures of Jacquin, who, having seen them 

 only in this state, naturally considered these plants as truly gynandrous, regarding the 

 masses of pollen as the antherse, originating in the glands of the stigma, and merely 

 immersed in the open cells of the genuine antherae, which he calls antheriferous sacs; an 

 opinion in which he has been followed by Rottboell, Koelreuter, Cavanilles, Smith, and Des- 

 fontaines. The conclusion to be drawn from the observations now detailed is sufficiently 

 obvious ; but it is necessary to remark, that these observations do not entirely apply to 

 all the plants which I have referred to the Asclepiadese ; some of them, especially 

 Periploca, having a granular pollen, applied in a very different maimer to the glands of 

 the stigma ; they all, however, agree in having pollen coalescing into masses, which are 

 fixed or applied to processes of the stigma, in a determinate manner ; and this is, in 

 fact, the essential character of the Order. Dr. Smith, in the second edition of his 

 valuable Introduction to Botany, has noticed my opinion on this subject : but, probably 

 from an indistinctness in the communication, which took place in conversation, has 

 stated it in a manner somewhat different from what I intended to convey it to him ; 

 for, according to his statement, the pollen is projected on the stigma. The term 

 projection, however, seems to imply some degree of impetus, and at the same time 

 presents the idea of something indeterminate respecting the part to which the body 

 so projected may be applied. But nothing can be more constant than the manner in 

 which the pollen is attached to the process of the stigma in each species." 



Erown who first distinguished Asclepiads, stated that they differed solely in the 

 peculiar character of their sexual apparatus ; but this was of so unusual a kind in 

 Asclepiads, as to justify a deviation from the general rule, that Orders cannot be 

 established upon solitary characters. In Dogbanes the stamens are distinct, the 

 pollen powdery (that is to say, in the ordinary state), the stigma capitate and 

 thickened, but not particularly dilated, and all these parts distinct the one from the 

 other. But in Asclepiads the whole of the sexual apparatus is consolidated into a 

 single body, the centre of which is occupied by a broad disk-like stigma, and the 

 grains of pollen cohere in the shape of waxy bodies attached finally to the 5 corners 

 of this stigma, to which they adhere by the intervention of peculiar glands. 



The Order is one of those which contain indifferently what are called succulent plants 



