120 NEOTTE^. Chap, IV. 



and firmly cemented to their heads. As soon as the 

 insect flies away, it withdraws the pollinia, carries 

 them to another flower, and there leaves masses of the 

 friable pollen on the adhesive stigma. 



In order to witness what I felt sm-e would take 

 place, I watched for an hour a group of plants on 

 three occasions; each time I saw numerous speci- 

 mens of two small Hymenopterous insects, namely, a 

 Hsemiteles and a Cryptus, flying about the^plants and 

 licking up the nectar ; most of the flowers, which were 

 visited over and over again, already had their pollinia 

 removed, but at last I saw both these species crawl 

 into younger flowers, and suddenly retreat with a pair 

 of bright yellow pollinia sticking to their foreheads ; I 

 caught them, and found the point of attachment was to 

 the inner edge of the eye ; on the other eye of one 

 specimen there was a ball of the hardened viscid 

 matter, showing that it had previously removed 

 another pair of pollinia, and in all probability had subse- 

 quently left them on the stigma of a flower. As these 

 insects were captured, I did not witness the act of fertili- 

 sation; but Sprengel saw a Hymenopterous insect 

 leave its pollen-mass on the stigma. My son watched 

 another bed of this Orchid at some miles' distance, and 

 brought me home the same Hymenopterous insects 

 with attached pollinia, and he saw Diptera also 

 visiting the flowers. He was struck with the number 

 of spider-webs spread over these plants, as if the 

 spiders were aware how attractive the Listera was to 

 insects. 



To show how delicate a touch sufiices to cause 

 the rostellum to explode, I may mention that I found 

 an extremely minute Hymenopterous insect vainly 

 struggling to escape, with its head cemented by the 

 hardened viscid matter, to the crest of the rostellum 



