Chap. II. HEEMINIUM MONOBCHIS. 61 



like odour. They seem higMy attractive to insects ;• in 

 a spike with only seTen flowers recently open, four had 

 both poUinia, and one had a single poUinium removed. 

 When the first edition of this book appeared I did 

 not know how the flowers were fertilised, but my son 

 George has made out the whole process, which is 

 extremely curious and differs from that in any other 

 Orchid known to me. He saw various minute insects 

 entering the flowers, and brought home no less than 

 twenty-seven specimens with pollinia (generally with 

 only one, but sometimes with two) attached to them. 

 These insects consisted of minute Hymenoptera (of 

 which Tetrastichus diaphantus was the commonest), 

 of Diptera and Coleoptera, the latter being Malihodes 

 hrevicolUs. The one -indispensable point appears to 

 be that the insect should be of very small size, the 

 largest being only the -^ of an inch in length. The 

 pollinia were always attached to the same place, 

 namely, to the outer surface of the femur of one of the 

 front legs, and generally to the projection formed by 

 the articulation of the femur with the coxa. The 

 cause of this peculiar mode of attachment is suffici- 

 ently clear : the middle part of the labellum stands so 

 close to the anther and stigma, that insects always enter 

 the flower at one corner, between the edge of the 

 labellum and one of the upper petals; they also almost 

 always crawl in with their backs turned directly Or 

 obliquely towards 'the labellum. My son saw several 

 which began to crawl into the flowers in a different 

 position ; but they came out and changed their posi- 

 tion. Standing in either corner of the flower, with 

 their backs turned towards the labellum, they insert 

 their heads and fore legs into the short nectary, which 

 is seated between the two widely separated viscid discs. 

 I ascertained that they had occupied this position by 



