Dansk Botanisk Arkiv, Bd. 2 Nr. 10. 



several other investigators often have found the corpusculum fixed 

 upon the pulvillus. Without a microscopic observation, at any rate, 

 it cannot be decided, where the corpusculum is fixed, and we may 

 add that this observation must be very careful. At a cursory obser- 

 vation under the microscope, it may often appear as if the corpus- 

 culum is fixed upon a claw, even if it is fixed upon the pulvillus. 

 Nevertheless one ought perhaps to accept the various observations 

 of the situation of the corpusculum upon the foot of the insect as 

 holding good severally, if it were not possible to approach the 



question still more, viz. 

 by trying if it is possible 

 to fix the corpusculum 

 upon a claw. It is easy 

 enough to make the ex- 

 periment bypassing a claw 

 up through the fissure of 

 the anthers. By this ex- 

 periment one may, it is 

 true, pull out the corpus- 

 culum, but I at least have 

 never succeeded in making 

 the corpusculum fix upon 

 a claw. The reason of this 

 I believe to be, partly,that 

 a certain flexibility of an 

 organ is required to enable 

 it to pass up through the 

 fissure of the corpuscu- 

 lum, the edges of the lat- 

 ter over lapping, and this 

 flexibility the stiff claw 

 does not possess, partly, that the claw most probably is too clumsy 

 to be able at all to pass through the tiny fissure of the corpusculum. 

 It remains to discuss Robertson's finding corpuscula upon 

 the stiff hairs of the foot. None of the naturalists, who have in 

 Europe examined the insects that pollinate A. cornuti, have found 

 corpuscula upon the stiff hairs of the foot of the insect. In the bot. 

 garden of Copenhagen I found corpuscula fixed upon the foot of 

 bees above the claws; these corpuscula, however, were not fixed 

 directly upon the stiff hairs, but upon appendages of corpuscula of 

 Asclepias incarnata, which were in their turn fixed upon the stiff 

 brushes. The species A. incarnata is growing next to A. cornuti. A. 



Fig. 1. 

 A. Foot of humble-bee with corpusculum. 

 The foot is seen from below X 3. B. Flower 

 of Asclepias cornuti, upon which the foot 

 of a humble-bee has been placed in the 

 position which it occupies, when the humble- 

 bee is extracting the corpusculum. X 20. 

 C. Corpusculum seen from the outside. 



X 50. 





