Fecundation in Orchidee and Asclepiadee. 719 
of the distinct origins of these parts is very satisfactorily shown, 
in accordance with my observations in the essay referred to*. 
But in these drawings Mr. Bauer has gone further than I 
did, having also represented the internal structure of the pollen 
mass as cellular; each cell in the flower-bud just before expan- 
sion being filled with a grain of pollen, marked with lines indi- 
cating its quaternary composition ; while in the expanded flower 
this grain is exhibited as shrivelled, having discharged its con- 
tents, which consist of a mixture of an oily fluid and minute 
granules. From this, the concluding stage of the series, it 
may be inferred that Mr. Bauer's opinion respecting the mode 
of impregnation in Asclepiadez agrees with that which I had 
adopted, and which, though probably originating with Richard 
in 1779*, and briefly stated by him in 18021, was first distinctly 
expressed as a conjecture in 1789 by M. de Jussieu. 
In 1817, Mr. Stephen Elliott states that he observed, in his 
Podostigma§,—a genus nearly allied to Asclepias,—a fibre or 
cord extending through the centre of the corpuscular pedicel or 
attenuated base of the stigma, and communicating from the 
anthera to the ovarium. He adds, that Dr. Macbride has since 
seen it in some species of Asclepias. 
There can be no doubt that the cord here noticed is of the 
same nature with that which Gleichen has described in a diffe- 
rent state, and of which I shall presently have occasion to speak. 
* In a flower-bud much earlier than the commencement of Mr. Bauer's series 1 
have found the pistilla to consist merely of two distinct very short semicylindrical 
bodies, the rudiments no doubt of the future stigma. ; 
In this stage also the antherz are flat, nearly orbicular or ovate, greenish, rather thick 
and opake, but petal-like, with no inequality of surface, or any other appearance of the 
future cells, which in a somewhat more advanced stage are indicated by two less opake 
areole, and at the same time the two semicylindrical bodies unite to form the stigma. 
(Pl. 36. fig. 7—11.) i + Encycl. Botan. i. p. 212. 
+ Bulliard, Dict. de Bot. ed. 2. p. 56. § Bot. of Carol. and Georg. i. p. 397. 
VOL. XVI. 4z In 
