314 Formation and Flora of a Shingle Island. [Sess. 



On such a place as our Shingle Island, the characteristic has 

 additional value ; for in times of flood, when slightly rooted 

 plants may be swept away, a creeping root entwined round 

 many pebbles gives its possessor a secure foothold and pre- 

 serves it in safety. 



We have not been able to confirm our results by tracing 

 any correspondence between the number of " qualifications " 

 any given plant possesses for reaching the island, and that 

 plant's actual numbers there. In order to trace such corre- 

 spondence, it would be necessary to calculate roughly the 

 number of individual plants of each species on the island. 

 We should have to take into account, also, other conditions, 

 such as the length of time the species had been resident on 

 the island, and its prolilicness ; and a further consideration is 

 this, that one way of reaching the island is quite enough to 

 ensure ultimate wide distribution there, provided that the 

 plant finds the island a suitable habitat, and produces plenty 

 of seed. We are similarly unable to trace a correspondence 

 between any given plant's " qualifications " for thriving in the 

 island, and its actual state there. Here, again, we should 

 require further information. For instance, we have set down 

 no "qualification" for thriving against the Aster hybrid; but 

 since it certainly is thriving, the omission merely indicates 

 our ignorance of what the qualification is, and not any 

 lack of qualification in the Aster. We trust, therefore, that 

 it is the insufficiency of our data, rather than any actual 

 error in our figures, which is responsible for this lack of 

 correspondence. 



The omissions in our lists, then, are not intended to carry 

 much weight, as they often (and especially in columns 5 and 6) 

 indicate nothing beyond ignorance of the factor in question. 

 All our positive statements in the lists, however, have been 

 made with great care, and verified from books wherever we 

 were able. 



In conclusion, we have to express our hearty thanks to the 

 friends who have helped us in various ways, — to Dr Cameron 

 of Dalmally ; to Mr H. F. Tagg of the Eoyal Botanic Garden, 

 Edinburgli ; and especially to Mr Peter MacVean, a crofter 



