258 BOTANY [Chap. X 



Letter 590 occurs in Lobelia or the Compositae. Finally the style emerges from the 

 indusium, 1 the stigmas open out and are pollinated from younger flowers. 

 The mechanism of fertilisation has been described by F. Miiller, 2 and 

 more completely by Delpino (loc. cit.). 



Mr. Bentham wrote a paper 3 on the style and stigma in the 

 Goodenovieas, where he speaks of Mr. Darwin's belief that fertilisation 

 takes place outside the indusium. This statement, which we imagine 

 Mr. Bentham must have had from an unpublished source, was incom- 

 prehensible to him as long as he confined his work to such genera as 

 Goodenia, Sccevola, Velleia, Ccelogyne, in which the mechanism is much 

 as above described ; but on examining Leschenaultia the meaning became 

 clear. Bentham writes of this genus : — " The indusium is usually described 

 as broadly two-lipped, without any distinct stigma. The fact appears to 

 be that the upper less prominent lip is stigmatic all over, inside and out, 

 with a transverse band of short glandular hairs at its base outside, while 

 the lower more prominent lip is smooth and glabrous, or with a tuft of 

 rigid hairs. Perhaps this lower lip and the upper band of hairs are all 

 that correspond to the indusium of other genera ; and the so-called upper 

 lip, outside of which impregnation may well take place, as observed by 

 Mr. Darwin, must be regarded as the true stigma." 



Darwin's interest in the Goodeniaceas was due to the mechanism being 

 apparently fitted for self-fertilisation. In 1871 a writer signing himself 

 F.W.B. made a communication to the Gardeners' Chronicle? in which he 

 expresses himself as " agreeably surprised " to find Leschenaultia adapted 

 for self-fertilisation, or at least for self-pollinisation. This led Darwin to 

 publish a short note in the same journal, 5 in which he describes the penetra- 

 tion of pollen-tubes into the viscid surface on the outside of the indusium. 

 He also describes how a brush, pushed into the flower in imitation of an 



1 According to Hamilton (Proc. Linn. Soc. N.S. Wales, X., 1895, P- 3 01 ) 

 the stigma rarely grows beyond the indusium in Dampiera. In the 

 same journal (1885-6, p. 157, and IX., 1894, p. 201) Hamilton has given 

 a number of interesting observations on Goodenia, SccEvola, Selliera, 

 Brunonia. There seem to be mechanisms for cross- and also for self- 

 fertilisation. 



2 In a letter to Hildebrand published in the Bot. Zeitung, 1868, 

 p. 113. 



3 Linn. Soc. Journal, 1869, p. 203. 



4 1871, p. 1103. 



5 1871, p. 1 166. He had previously written in the Journal of Horticul- 

 ture and Cottage Gardener, May 28th, 1861, p. 151 : — " Leschenaultia formosa 

 has apparently the most effective contrivance to prevent the stigma of one 

 flower ever receiving a grain of pollen from another flower ; for the pollen 

 is shed in the early bud, and is there shut up round the stigma within a 

 cup or indusium. But some observations led me to suspect that never- 

 theless insect agency here comes into play ; for I found by holding a 

 camel-hair pencil parallel to the pistil, and moving it as if it were a bee 



