Fecundation in Or chidecB and Asclepiadece. 719 



of the distinct origins of these parts is very satisfactorily shown, 

 in accordance with ray observations in the essay referred to*. 



But in these drawings Mr, Bauer has gone further tlian 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 Asclepiadeae agrees with that which I had 

 adopted, and which, though probably originating with Richard 

 in I779+, and briefly stated by him in 1802 J, was first distinctly 

 expressed as a conjecture in 1789 by M. de Jussieu. 



In I8I7, 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 mucli 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 antherae 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 

 areolae, and at the same time the two semicylindrical bodies unite to form the stigma. 

 (PI. 36. fig. 7—11.) t Encycl. Botan. i. p. 212. 



^ % Bulliard, Diet, de Bot. ed. 2. p. 56. § But. 0/ Carol. andGeorg. i. p. 327. 



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