Mr. C. Darwin on the Fertilization of Orchids. 149 



do this ; they always clung, whilst sucking the nectar, to the 

 distal and hinged half of the labellum, which was thus pressed 

 downwards. Owing to this part being elastic and tending to 

 spring up, the bees, as they left the flowers, seemed to fly 

 rather upwards ; and this would favour, in the manner explained 

 by me, the complete withdrawal of the pollen-masses, quite as 

 well as an insect crawling out of the flower in an upward 

 direction. Perhaps, however, this upward movement may not 

 be so necessary as I had supposed; for, judging from the point 

 at which the pollen-masses were attached to the bees, the 

 back part of the head would press against, and thus lift up, the 

 blunt, solid, upper end of the anther, thus freeing the pollen- 

 masses. 



Various other insects besides hive-bees visit this Epijjactis. 

 My son saw several large flies {8arcojphaga carnosa) haunting 

 the flowers ; but they did not enter in so neat and regular a 

 manner as the hive-bees ; nevertheless two had pollen-masses 

 attached to their foreheads. Several smaller flies [Cmlopa 

 frigida) were also seen entering and leaving the flowers, with 

 pollen-masses adhering rather irregularly to the dorsal surface 

 of the thorax. Three or four distinct kinds of Hymenoptera 

 (one of small size being Crabro hrevts) likewise visited the 

 flowers ; and three of these Hymenoptera had pollen-masses 

 attached to their backs. Other still more minute Diptera, 

 Coleoptera, and ants were seen sucking the nectar ; but these 

 insects appeared to be too small to transport the pollen-masses. 

 It is remarkable that some of the foregoing insects should 

 visit these flowers ; for Mr. F. Walker informs me that the 

 Sarcojjhaga frequents decaying animal matter, and the Coelopa 

 haunts seaweed, occasionally settling on flowers ; the Crabro 

 also, as I hear from Mr. F. Smith, collects small beetles {Hal- 

 ticce) for provisioning its nest. It is equally remarkable, see- 

 ing how many kinds of insects visit this Epipactis^ that, al- 

 though my son watched for some hours on three occasions 

 hundi'cds of plants, not a single humble-bee alighted on a 

 flower, though many were flying about. In a footnote I have 

 given the results of experiments made by Mr. More, by cutting 

 ofl" the distal and hinged half of the labellum, in order to as- 

 certain how far this part is important. He has now repeated 

 the experiment on nine additional flowers : of these, three did 

 not produce seed-capsules ; but this may have been accidental. 

 Of six capsules which were produced, two contained about as 

 many seeds as the capsules of unmutilated flowers on the same 

 plant; but four capsules contained much fewer seeds. The 

 seeds themselves were well-formed. These experiments, as 

 far as they go, support the view that the distal part of the 



