20 TRANSACTIONS AND PKOCEEDINGS OF THE [Sk.ss. lxv. 



on many islands, point to a much more remote period than 

 that which we are considering, but the extinction of the 

 White Beam, Pyrus Aria, as a native, and the present 

 rarity of Frmms Fadus and, perhaps. Viburnum O/mlus, 

 must be put down to the time we are considering. Herb- 

 aceous plants, as Luzida pilosa, which require shade, would 

 become locally extinct. The ef!ect on Hepatics would be 

 marked, and, to a less extent, on some species of Mosses. 

 As there have always been woods remaining in some places, 

 as well as other natural shelters, the total extinction of 

 species would be rare ; and during the latter half of the 

 century, with the increase of artificial woods, species which 

 require shelter would again find suitable places where hard 

 wood plantations were made. They would have little 

 advantage from the planting of conifers, as this form of 

 plantation until the age of maturity is detrimental to 

 undergrowth. The most important botanical effects of the 

 introduction of firs and larches is the introduction of species 

 of fungi, which only grow in the neighbourhood of these 

 trees. This can be seen at the present time in the High- 

 lands, in any place where such plantations have been made. 

 The distribution of weeds of agriculture must have much 

 altered since the eighteenth century. At that time crofter 

 holdings were more general over the country, almost every 

 piece of land which could possibly be cultivated bearing the 

 marks of this. Since that time what increase in extent 

 of cultivated land there may be has been mostly limited 

 to enlarging farms, and cultivated areas near farmhouses 

 and townships, so that instead of having cornfield weeds 

 generally distributed throughout the country, we now have 

 them almost limited to such farms and townships. The 

 reclamation of waste ground did not take place to any 

 extent until the introduction of potatoes. This was in 

 1743, the first locality being in the island of South Uist. 

 The idea of cleaning the fields from weeds was probably 

 first thought of in connection with potato culture, as the 

 Highlanders were then, as now, proverbially careless in this 

 matter. This would introduce a fresh factor in the distri- 

 bution of certain weeds, as these are generally thrown on 

 to the shores or into rivers ; and most of the surprises we 

 now see in the presence of agricultural weeds on or near 



