1890.] Notes on Cyphia Volubilis, Willd. 47 



proterandrous and cross-fertilisation must therefore as a rule take place 

 for the production of seeds. 



In Cyphia volubilis, however, the style has reached its final length 

 when the flower opens, and as no change is perceptible after the pollen 

 has been deposited on the top of the style even if it is examined with 

 a lens, I was for some time under the impression that we have here a 

 very marked case of self-fertilisation, which was the more strange as 

 all species of Campanuiaceae which have hitherto been examined 

 show very elaborate arrangements for cross-fertilisation, although self- 

 fertilisation is in many cases not excluded. The microscopic examin* 

 ation of the style, however, revealed some arrangements, which to say 

 the least must sometimes ensure cross-fertilisation and these arrange- 

 ments are quite unique as far as my knowledge goes. Any longitudinal 

 section through the upper portion of the style (Fig. x.) will show that 

 it contains a cavity in its thickened part, and if such a section be made 

 exactly in its median plane, it will reveal the existence of a narrow 

 channel at its posterior portion (Fig. x c), through which the cavity 

 communicates with the open air. I will call this cavity the " stigmatio 

 cavity." 



I said before that the anthers are placed closely together, and the 

 pollen is kept in the tube, which is formed by them. The slightest touch 

 on the anthers or filaments will, however, open the tube. Insects visiting 

 the flowers can therefore not fail to dust themselves with pollen if 

 they touch these parts, and as the pollen is frequently entirely removed 

 from the flowers, I do not think that we can imagine any other 

 agency which can effect this. At a comparatively early stage there 

 appear at the mouth of the stigmatic cavity drops of a slimy substance 

 (Fig. v e), and the cavity itself is also filled with the same substance, 

 which appears to be produced by the breaking down of the walls of 

 the cells lining the cavity, and of the hairs placed round the entrance, 

 in very much the same way as the slimy substances in many fruits 

 are formed. However, the exact nature and the precise mode of the 

 formation of this slime remain to be determined. In this slime we see 

 in older flowers a number of pollen grains germinating (Fig. x), and 

 the pollentubes pass from the cavity into the " conducting tissue " of 

 the style. I have never seen a poller. tube passing from the top of 

 the style into it although I have diligently searched for such cases, 

 and although it sometimes happens that a few pollengrains which have 

 been left there, begin to push out their tubes. It will now be 

 apparent why I have called the cavity " the stigmatic cavity." It 

 acts like a stigma by receiving the pollen for fertilisation by giving it 

 an opportunity of germinating -and* allowing the pollentubes to pass 

 into the style. The question now arises what is the biological 



