

Bd.2 . DANSK BOTANISK ARKIV • Nr.io 



UDGIVET AF DANSK BOTANISK FORENING 



= 1919 = 



I. The Pollination of Asclepias cornuti Dcne. 



By LIRKARY 



Holger Jørgensen. new y^kk 

 BOTANICAL 



JN one of the descriptions of the pollination of Asclepias cor- 

 nuti, which we have got, are quite satisfactory as regards the condi- 

 tions of the insects, because none of them are founded upon direct 

 observations. 



The foundation of most of the descriptions is evidently con- 

 fined to an observation of where upon the insect the corpusculum 

 (Co RR y) [the stigmatic gland (Rob. Brown), Klemmkörper of the 

 German authors] is fixed. In the work by Hildebrandt (1) and 

 in contemporary works by Müller (2) and others, as well as in a 

 later work by Corry (3), the pollinating insect is said to get its foot 

 into the fissure of the anthers (alar chamber (Corry), Germ. Nar- 

 benkammer) below, so that the foot is drawn up through the latter, 

 by which means the corpusculum fixes upon one of the claws of 

 the foot. It is, however, easy to see that the foot of the insects, we 

 are here concerned with, is too big to be drawn up through the 

 fissure of the anthers. So it is only from the situation of the corpus- 

 culum upon the insect that the above-mentioned investigators have 

 judged about the whole condition of the insect during the pollina- 

 tion. Moreover the observation of the situation of the corpusculum 

 is most probably erroneous. In recent literature sufficient informa- 

 tion is found to make it a matter of doubt whether the corpusculum 

 is able at all to be fixed upon a claw. Neither Hildebrandt nor 

 Müller has given any illustration of legs of insects with cor- 

 puscula. It is true that Corry has done so; but in the first place 

 it is the foot of a fly, which is figured, though he, as well as the 

 earlier investigators, has found that bees are the only pollinators, 

 and, secondly, the corpusculum upon this foot of a fly is fixed, not 

 upon a claw, but upon one of the pulvilli. 



Dansk Botanisk Arkiv, Bd. 2 Nr. 10. 1 



