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Facts relating to the Tormentilla officinalis. By Dr E. D. Thomson. 



The following tables have been drawn up from observations on tbe 

 Tormentilla officinalis^ which were made with the view of contributing 

 to the determination of a question which has interested most botanists 

 — whether the genus Tormentilla should be considered as distinct from 

 Potentilla, or whether the species of the former genus should be ranked 

 under the latter. I have seen observations somewhat similar, but 

 upon a less particular plan, than those I have detailed, for nothing has 

 hitherto been related regarding the soils upon which the different 

 specimens examined had vegetated, which must be considered of very 

 considerable importance in determining the effect of soil in increasing 

 or diminishing the number of petals. The plants subjected to exami- 

 nation were collected on four distinct formations, viz., 1. Mica-slate, 

 2. Old Eed Sandstone, 3. New Red Sandstone, and 4. Diluvium. By 

 the latter term is to be understood the gravel left by the retiring of 

 Loch Lomond, on the west side of that lake, on the road from Helens- 

 burgh to Luss, which passes through numerous artificial-looking 

 tumuli, presenting a rounded outline. A careful search satisfied me 

 that these were formerly islands in the lake, similar to those which 

 now vary so beautifully its surface, and which have been left as 

 isolated hillocks by the gradu.al di'aining of the lake. The gravel 

 consists of clay-slate. The new red sandstone at Helensburgh is 

 formed of fragments of clay-slate, imbedded in clay, obviously a pro- 

 duct of the disintegration of the clay-slate rocks, and is overlaid in 

 general by a stiff reddish soil. The new red sandstone of Berwick- 

 shire appears to be closely connected with the carboniferous series. 

 These observations seem necessary in order that the subsequent facts 

 may be better appreciated. 



