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



The only naturalist, who has made a closer study of the condi- 

 tions of the insect during the pollination, is Robertson (4), who 

 studied the pollination in America; but not even Robertson tried 

 any direct observation. His results were got by the examination 

 of the pollination of a species of Asclepias with greater flowers, 

 Asclepias Sullivantii. In this species R. often found hive -bees captiv- 

 ated, and he then noticed that the insect did not stick with the whole 

 of its foot in the fissure of the anthers but with one claw or the 

 pulvillus. R. then assumed the case to be the same in other species 

 of Asclepias, e. g. in A. cornuti, viz. that the insects do not get the 

 whole of the foot into the fissure of the anthers, but only the part 

 upon which the corpusculum fixes. In the case of A. cornuti it is 

 stated that the corpuscula may be found upon the claws of the 

 insects, upon the pulvillus and the stiff hairs of the foot. 



The last data, as far as I am aware, about the pollination of 

 Asclepias cornuti are found in Zander's "Die Biene" from 1913, 

 rather an exoteric work. Zander holds that the corpusculum 

 always fixes upon the pulvillus, and figures the foot of a bee with 

 the corpusculum fixed there. The extraction of the pollen-mass 

 apparatus is described as follows: the insect gets its foot into the 

 fissure of the anthers, and when the foot has got a little way up, it 

 slips out, and the pulvillus gets up into the corpusculum. This de- 

 scription is not adequate, as it is not easy to understand, why the 

 pulvillus should just get hold of the corpusculum, when the foot 

 had got out of the fissure of the anthers. 



All existent works agree about the question, which irisects 

 perform the pollination; it is everywhere hymenopters: 



. • Bombus Coelioxys Scolia 



mellifica 

 Delpino X 



Müller X 



Hildebrandt 



Corry X 



Robertson X 



Zander 



In the bot. gard. of Copenhagen . 



Further there is unanimity that the insects perform the polli- 

 nation by means of the foot. The foot of the pollinating insects is 

 built alike, ending in two moveable claws, between which there is 

 a .little plate, the pulvillus. 



