88 HE PORT— 1867. 



III. That foresters and tanners regard Liclien-coated oak-bark as of diminished 

 value l)y virtue of such coatinp:. 



IV. That arboricultimsts consider Lichen-growth, a disease, or as a cause or rcs^tlt 

 of disease. 



Evidence is unanimous that Lichen-growth should never occur in forests or nur- 

 series which are the subject of proper care ; where the conditions of healthy growth 

 are sedulously provided ; where the trees or shrubs are properly thinned : where the 

 soil and manure are suitable. Further, the disease of Lichen-growth, when it ap- 

 pears, can be removed or dissi])ated at will by placing the tree which it affects in 

 more favourable conditions of development, such as transfer to a richer soil or the 

 supply of proper manure. 



On Plant- Acclimatization in Scotland, ivith special reference to Tussac Grass*. 

 Bij W. Laudee Lindsay, M.D., F.R.S.E., F.L.S. 



In ]\Iay 18GG the author inspected the condition of the Tussac-grass plantations 

 that had been established in 1845 by J.imes Eitchie, C.E., of Perth, ou the estates 

 of Sir Jiinics Mathcson in the Lews (Outer Hebrides). The main objects of his 

 communication were on the one hand to describe the condition of limited planta- 

 tions of a most nutritious and valuable exotic grass, which is capable of luxuriant 

 growth on otherwise sterile shores in Scotland, and on the other to illustriate 

 certain points in connexion with plant-acclimatization in Scotland that have not 

 attracted that degTee of attention which they deserve, viz. : — 



I. The necessity, as regards success, in acclimatization-experiments for imitatiiir/ 



tlie natural conditimis of f/rvicth ; and 



II. The inevitable failure that must residt from ignorance of or inattention to these 



conditions. 



From all the evidence he had collected, the author's conclusion was that the 

 Tussac experiment in the Lews was on the whole a fiiilurc, but one due solely to 

 inattention to the proper care and cultivation of the grass. Tussac roqiures protec- 

 tion and care like other crops, and not more so. Sxutable regulations for both pro- 

 tection and care were laid down by Mr. liitchie ; and so long as these were carried 

 out or attended to, the plantations thrived, and they only failed after he left the 

 island, and the conduct of the experiment was consigned to those who had a less 

 intelligent conception of its importance, and an infeiior interest in its success. The 

 immediate causes of the destruction of the crops of Tussac, wliich were flourishing 

 in 1852, appear to have been (1 ) non-protection by fences, and ( 2) the Avaut of weed- 

 ing. Cattle were allowed unlimited access, with the result that the plant was de- 

 stroyed, partly by being trampled down, partly by the roots being grubbed up and 

 eaten. Weeding was not attended to, and in general terms no care was bestowed 

 on its cidtivation. 



The author believes there is no ground for doubting that tcith the same amount of 

 care as is bestowed on other crops, such as turnips, Tussac grass may be successfully 

 cultivated on many of the bleak and sterile islands and coastsof Scotland, to which 

 it could not fail to become a boon of no iusiKnificant kind. 



To wJiat extent is Liclien-qrowth a test of Aeje? 

 By AV. Latjdek Lindsay, M.D., F.ll.S.E., F.L.S. 



The opinion is, and has been long prevalent among poets, historians, and archajo- 

 logists, that trees and buildings are aged in proportion to the copiousness of their 

 Lichen-covering ; that Lichen-growth may be regarded as a test of the antiqiuty of 

 the natural objects or artificial structures on -N^'hich it occurs. Poets constantly 

 speak of trees, rock.s, or towers as being " mossed -Kith ae/c ;' while archreologists 

 have gone so far as to consider Lichen-growth diaf/nustic of antiquitv. The popular 

 name of Lichens, " Time-stains," shows that .such a belief is, however, by no means 

 confined to tlie classes of writers referred to. Eotanical writers have fostered this 

 belief by almost uniformly describing Lichens as of very slow growth, attaining to 



* The subject may be found treated at greater length in the ' Jouiual of jigriculturc,' 

 November 18C7; or the ' Farmer,' Oct. CO, 18G7, p. 553. 



