406 BRITISH FLOWERING PLANTS chap. 



side, and alters the direction of the pollen mass, thus 

 bringing it (as in Orchis mascula) into such a position, 

 that it comes in contact with the stigmatic surface of 

 the flower to which it is carried. The poUinia attach 

 themselves at the side of the insect's face. 



H. bifolia. — This is one of the white species which is 

 especially adapted to moths, and is particularly sweet- 

 scented at night. The spur is 13-20 mm. in length. 

 It is regarded by Bentham and other high authorities 

 as a mere variety of the last. Yet, as Darwin points 

 out, it differs in many important particulars. The 

 viscid disks are oval, and almost touch ; the viscid 

 matter itself is of somewhat different character ; the 

 drum -like pedicel is rudimentary ; the stalk of the 

 pollen mass is much shorter ; the packets of pollen 

 shorter and whiter ; and the stigmatic surface more 

 distinctly tripartite. It would certainly seem, therefore, 

 that the two species are distinct. The poUinia attach 

 themselves at the base of the proboscis, not on the side 

 of the face. 



H. albida. — In this species the spur is very short, 

 but so narrow that it is probably adapted to small 

 moths. 



ACERAS 



A. anthropophora (Man Orchis). — The arrangements 

 of the flower resemble those of 0. mascula. 



Herminium 



The perianth has no spur, and the anther cells are 

 distant at the base. 



H. Monorchis. — The pollen masses are short and the 

 disks large. It does not produce honey, but is very 

 sweet-scented at night, so that it is probably a moth 

 flower. G. Darwin, however, and H. Miiller found it 

 visited during the day by ichneumons and small beetles. 

 The poUinia attach themselves to the joint between the 

 femur and the trochanter of the first pair of legs.^ 



^ Darwin, More Letters. 



