THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. So.'i 



that this supply is not lost prematurely by evaporation. As a matter <>t fact, such 

 detached offshoots, e.g. those of Sempervivum, Sedum, Kleinia, or Mnin'dlat-ia, 

 are not only provided with a special aqueous tissue, but also with a cuticle which 

 is very effective in preventing excessive transpiration. All offshoots, when liberal- -1 

 from their place of origin, are also provided with the necessary reserves, i.e. con- 

 structive materials, so that immediately after settling, they can send out absorbent 

 roots and green leaves of their own initiative, obtain a firm footing in their new 

 locality, and extract nourishment from it. When the offshoots are distributed by 

 water-currents, they require neither an aqueous tissue nor protection against drying 

 up, and it may be due to this fact that detached offshoots are relatively more fre- 

 quent in aquatic than in land plants and lithophytes. 



THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. 



On the heights of the Kahlenberg, at Vienna, at the edge of the wood, grows 

 an under-shrub which bears the name of Dorycnium herbaceum. It is one of the 

 Papilionaceae, and develops spherical one-seeded fruits, which ripen in October. 

 I once collected from this plant several twigs laden with fruit, for the purpose of a 

 comparative investigation on which I was engaged, and brought them home and 

 laid them on my writing-table. Next day as I sat reading near the table, one of 

 the seeds of the Dorycnium was suddenly jerked with great violence into my 

 face. Shortly afterwards I saw a second, third, fourth, and ultimately about 

 seeds let fly from the small clusters of fruit, and each time I heard a peculiar 

 sound which accompanied the bursting open of the fruits and ejection of the * 

 The rays of sunshine from the window had evidently heated and dried the i 

 and occasioned this surprising phenomenon. The incident reminded me of 

 following passage in Goethe's Travels in ltaly:-"I had brought home seven 

 seed-capsules of Acanthus mollis, and put them away in an open box, when o 

 night I heard a crackling noise, and immediately afterwards a sound 

 impact of small bodies against the walls and ceiling. \^^f 

 first but found afterwards that my pods had burst and scattered their seeds al 

 over* the place. The dryness of the room had caused the fruits to ripe, 



X" tzf ^r^'rit ^ ,. - . - . ^ 



group designated by tl name of Sling-fruit. It is found that J^t* * 



are ripe the tissue around the seeds becomes highly tense. The first 



tens Ini that the tissue is rent at particular spots, and this rupture is followe 



& VOL. II. 



