Mr. C. Danvin on the Fertilizatiun of Orchiih. 11 



insects, and are gnawed by them, as in the case of many 

 Vandeas and other exotic orcliids. 



Goodyera rejJens (p. 114). — Mr. K. B. Tliomson informs me 

 that in the north of Scotland lie saw many humble-bees visit- 

 ing the flowers and removing the pollen-masses, which were 

 attached to their proboscides. The bee sent was Bomhus jjra- 

 torum. This species grow.s also in the United States ; and 

 Prof. Gray (Amer. Journ. of Science, vol. xxxiv. 1862, p. 427) 

 confirms my account of its structure and manner of fertiliza- 

 tion, which is likewise applicable to another and very dis- 

 tinct species, namely, Goody era pubescens. Prof. Grray states 

 that the passage into the flower, which is at first very nan-ow, 

 becomes, as I suspected, more open during its older state. 

 Prof. Gray believes, however, that it is the column, and not 

 the labelhun, wliicii changes its position. 



Sjnranthes autumnalis (p. 123). — As in the case of the 

 Goodyera, Prof. Gray feels confident that it is the column which 

 moves from the labellum as the flower grows older, and not, 

 as I had supposed, the labellum which moves from the column. 

 He adds that this change of position, which plays so important 

 a p)art in the fertilization of the flower, " is so striking that 

 we ^vender how we overlooked it" (Amer. Journ. of Science, 

 vol. xxxiv. p. 427). 



On the rosteUum o/Listera ovata not exploding spontaneoiisly 

 (p. 149). — 1 have covered up some additional plants, and found 

 that the rostellum lost its po\\-er of explosion in about four days, 

 the viscid matter tlien turning brown within the loculi of the 

 rostellum. The weather at the time was unusually hot, and 

 this may have hastened the process. After the four days had 

 elapsed, the pollen had become very incoherent and some had 

 fallen on the two corners, or even o\-er the wlsole surface, of 

 the stigma, which was j^enetrated by the pollen-tubes. Hence, 

 if insects should fail to remove the pollinia by causing the 

 explosion of the rostellinn, this orchid certainly seems capable 

 of occasional self-fertilization. But the scattering of the in- 

 coherent pollen was largely aided by, and perhajjs wholly de- 

 pended on, the presence of Thrip^ — insects so minute that 

 they could not be excluded by any net. 



Listera cordata (p. 152). — Prof. Dickie has been so good as 

 to observe the flowers on living plants. He informs me that, 

 when the pollen is mature, the crest of the rostellum is di- 

 rected towards the labellum, and that, as soon as touched, the 

 viscid matter explodes, the poUinia becoming attached to the 

 touching object ; after the explosion, the rostellum bends 

 downwards and spreads out, thus ]n-otecting the virgin stig- 

 matic surface ; subsequently the rostellum rises and exposes 



