IN ORCHIDE^ AND ASCLEPIADE^. 519 



undivided cavity, filled with minute granular matter mixed 

 with an oily fluid; and hence concluded that the fe- 

 cundating matter was conveyed from the mass through the 

 arm and gland to the stigma. 



In the month of April last I saw, foT the first time, 

 drawings of several Asclepiadese made between 1805 and 

 1813 by Mr.- Bauer, who, aware of the interest I took in 

 this subject, with his accustomed liberality and kindness, 

 offered me any part of them for publication. 



Among these drawings, exceeding perhaps in beauty and 

 in the completeness of the details all the other productions 

 with which I am acquainted even of this incomparable 

 artist, an extensive series, exhibiting the gradual develop- 

 ment of the parts of the flower in Asdepias ciirassavica, 

 were the most important. 



In this series, made in 1805, and commencing when 

 the poUen is just separable in a pulpy mass from its cell, 

 the glands of the undivided stigma being still invisible, the 

 fact of the distinct origins of these parts is very satis- [7i9 

 factorily 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 expansion being filled with a grain of pollen, marked 

 with lines indicating its quaternary composition ; while in 

 the expanded flower this grain is exhibited as shrivelled, 

 having discharged its contents, which consist of a mixture 

 of an oily fluid and minute granules. Prom this, the con- 

 cluding stage of the series, it may be inferred that Mr, 

 Bauer's opinion respecting the mode of impregnation in 

 Asclepiadese agrees with that which I had adopted, and 



' In a flower-bud much earlier than the commenc^.i.ent of Mr. Bauer's 

 series I have found the pistilla to consist merely of two distinct very short 

 semicjlindrical bodies, the rudiments no doubt of the futiiie stigma. 



In this stage also the antherse are flat, nearly orbicular or ovate, greenish, 

 rather thick and opaque, 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 opaque areolae, and at the same time the two semi- 

 cylindrical bodies unite to form the stigma. (PI. 36, figs. 7 — 11.) 



