GERMINATION OF SEEDS. 591 



water without injury. In 1843 ^^e channels of Poole 

 Harbour were deepened, the mud raised being- deposited 

 on the shore, covering several hundred square yards ; a 

 quay was made from the hardened mud : this was never 

 used, and the surface was not disturbed. Early in next 

 spring the surface exhibited abundant vegetation of char- 

 acter totally distinct from that of the flora of the neigh- 

 bouring shore, containing plants that did not grow within 

 many miles, and one probably foreign to the county. It 

 seemed conclusive to Salter that the seeds must have 

 been in the mud when deposited ; he concludes that the 

 seeds fell into tv/o rivers that flow into the harbour, and were 

 ultimately deposited in the channels. The evidence given 

 supports this view strongly ; if his hypothesis be accepted, 

 the seeds must have evidently suflered prolonged submer- 

 sion both in fresh and salt water without losing * vitality '. 

 But however complete this kind of evidence may be, it is 

 never conclusive, and, as with all induction, can only ap- 

 proximate to truth on reiterated confirmation. 



Salter's views are, however, supported by observations 

 of White (3). Mud was dredged from the Avon-bed and 

 the floor of the basins at Bristol by local officials ; this was 

 emptied into a disused quarry, the work being done by 

 manual and mechanical agency only. About half an acre was 

 thus covered to a depth of from ten to twenty feet. In next 

 spring a profuse and varied vegetation appeared ; many of 

 the species were native on the banks of the Avon above and 

 below Bristol, but had not been found previously at or near 

 this spot. There were also species recorded to grow in 

 the Avon valley, but which had become extinct or ex- 

 tremely rare, as also others not noted before in the district, 

 and some from all quarters of the globe. After comparing all 

 the evidence at his disposal, White concluded that the seeds 

 had been in the mud. This view is as justifiable as that of 

 Salter's, and is open to the same objections. Some seeds may 

 have lain lonsf in the mud, others but a short time ; there is 

 no means of settling in any case the duration of submersion, 

 and a safe criterion of judgment as to their origin does not 



and, moreover, from the nature of the case, cannot exist. 



40 



