1888-89.] Fertilisation of Aspidistra elatior hy Slugs. 497 



opportunity has been taken of making further observations, 

 and of reading Hildebrand's paper on F. Delpino's " Weitere 

 Beobachtunoen liber die Dichou;amie ini Pfianzenreich," in Bot. 

 Zeit., Jahrg. xxviii., 1870, which contains (p. 588) a dis- 

 course on our plant. Flowers were met with, having four 

 equidistant apertures at the margins of the fresh stigmas 

 (in front of alternate segments) leading into the pollen- 

 chamber. These vary from a mere pin-hole or slit to an 

 opening capable of admitting a young slug. The presence of 

 these apertures does not necessitate any alteration of the 

 views previously maintained. Slugs are still clearly the best 

 adapted agents in the case. Of course, the possibility of 

 self-pollination is here greatly increased during the exit of 

 the slug. The pollen, however, first deposited on the stigma 

 is in many cases likely to be that brought from another 

 Hower. Delpino describes a flower having the four little 

 openings by which small Milcken (gnats or craneflies), 

 " probably the pollinating insects," pass. He did not 

 actually find them in the cavities, but noticed what he 

 considered traces of their visits in flowers three or four days 

 open, not only the margins of the openings being smeared 

 with pollen, but also tracks of it being present in their vicinity. 

 Further, he seems to have observed that a small spider had 

 spun over the stigma a web with threads so fine that they could 

 not be detected unless by means of the pollen grains adhering 

 to them, and he regards this as favouring the view that 

 insects are frequent visitors. 



All this may reasonably be demurred to. Insects of the 

 kind indicated are not adapted in any respect whatever for 

 the work ascribed to them. As to the spider's webs, it may 

 be held as certain that the fine threads seen by Delpino 

 correspond to those often seen during the course of the 

 present observations, which were simply very delicate 

 filaments of mucus, with pollen-grains entangled, left by a 

 slug in its peregrinations. 



The significance of the heteromorphic condition of the 

 stigma (that is, with or without apertures) is not evident. It 

 may be surmised that the tendency of modification is towards 

 the complete closing in of the pollen chamber by the stigma. 



