120 TRANSACTIONS. XATUKAL HISTORY SOCIETY OK GLASGOW. 



a ball and none of the hooks being exposed. Close 

 examination of the booklets of Myosotis, Geum, 

 Agritnonia, Torilis, etc., shows that the point of the 

 hook is not properly formed till the very last 

 moment. As these slender projections dry, they not 

 only curve and spread, but a slight torsion also 

 occurs. On account of this twisting, the curve of 

 the hook ceases to be circular and becomes slightly 

 spiral, reminding one of the nutating tip of a 

 climbing stem. The curvature of the terminal part 

 of the catch is not all in one plane, but, like a 

 fish-hook, the point is turned a little to one side. 

 By this torsion of the spines their points become 

 fully exposed, and this explains how these appen- 

 dages so suddenly acquire' the property of taking 

 hold of one's clothes when the seeds are ripe. 



The exterior of some seeds becomes slimy or 

 mucilaginous when moistened, as in Poletnonium, 

 Pittosporum, Collomia, Teesdalia, Liniim, etc. But 

 this property does not appear to play an important 

 part in dispersion. It serves rather to fasten the 

 seed to the soil, and so assist the germinating radicle 

 in penetrating downwards. Mistletoe seeds have this 

 viscid character. The semi-parasitic habit of the 

 plant necessitates this provision, for an ordinary dry 

 seed, even if dropped by a bird on the branch of 

 a tree, would almost inevitably fall off again. 

 Arceutliohium, an allied genus which is parastic on 

 junipers, throws its seeds from one tree to another, 

 and the seed thus thrown adheres by means of its 

 viscid surface. Apparently for the same reason 

 several other epiphytes are provided with vis(!id seeds. 

 This adhesive property is, however, occasionally 

 utilised for dispersion by animals. Among others, 

 Hildebrand mentions, Cardutts pycnocephalus, Car- 

 pesium cermmm, Hymenostomu?}i Fontanesil, PumiUo 

 argyrolepis, Ruckeria, Trichocline, and the labiates 

 Ocymum Basilicum and Dracocephalum Moldavica. 



The outside of the fruit of Linncea horealis, and 

 the calyx of Phimhago, are studded with glandular 



