Mr. C. Darwin on the Fertilization of Orchids. 145 



sj^ontaneously fall out. lie a])pears to think that I infer that 

 this Ophrys fertilizes itself, which is an error. 



Ophrys apifera (p. 71). — Prof. Treviranus at first doubted 

 (Botanische Zeitung, 1862, p. 11) the accuracy of my account of 

 this Ophrys, and of the differences between it and 0. arach- 

 nites] but he has subsequently (Bot. Zeit. 1863, p. 241) fully 

 confirmed all that I have stated. 



Ophrys arachnites (p. 72). — I have now examined several ad- 

 ditional living specimens of this Ophrys, and can confirm my 

 statement that the pollinia do not fall out of the anther-cases, 

 even when the spikes are strongly shaken ; nor do they fall 

 out when the spikes are kept standing in water for a weelc. 

 Mr. J. Moggridge has made (Journ. Linn. Soc, Bot. vol. viii. 

 1865, p. 258) a remarkable observation on 0. scolopax, which 

 is closely allied to 0. arachnites, — namely, that at Mentone it 

 never exhibits any tendency to self-fertilization, Avhilst at 

 Cannes all the flowers fertilize themselves, owing to a slight 

 modification in the curvature of the anther, which causes the 

 pollinia to fall out. This botanist has given, in his ' Flora of 

 Mentone,' a full description, with excellent figures, of 0. scolo- 

 pax, arachnites, araaifera, and apifera ; and he believes, from 

 the number of intermediate forms, that they must all be 

 ranked as varieties of a single species, and that their differ- 

 ences are intimately connected with their period of flowering. 

 It does not appear that these forms in England, judging from 

 their distribution, are liable to pass into each other, within any 

 moderate or observal)le ])eriod of time. 



On the fertilization of Ilerminium monorchis (p. 74). — My 

 son, Mr. George Darwin, has fully observed the manner of 

 fertilization of this minute and rare orchis. It differs from 

 that of any other genus known to me. He saw the flowers 

 entered by various minute insects, and brought home no less 

 than twenty-seven specimens with ])ollinia (generally with only 

 one, but sometimes with two) attached to them. These insects 

 consisted of minute Hymenoptcra (of which Tetrastichus dia- 

 phantus was the commonest), of Diptera and Coleoptera, the 

 latter being Malthodes hrevicollis. The one indispensable 

 point appears to be that the insect should be of very minute 

 size, the largest being only the ~ of an inch in length. It 

 is an extraordinary fact that in all the si)ecimen8 the pollinia 

 were attached to the same peculiar s])ot, namely, to the outer 

 side of one of the two front legs, to the projection formed by 

 the articulation of the fenuir with the coxa. In one instance 

 alone a poUinium was attached to the outside of the femur 

 a little beneath the articulation. The cause of this peculiar 

 manner of attaclnnont is sutficiently clear : the middle part 



