THOMAS HOPKIRK OF DALBETH. 245 



(Mespilus japonica) upon the common one (M. ger- 

 manica).'' Sprengel quotes Hopkirk, and adds that 

 it is certain that evergreens may be propagated on 

 plants that are deciduous, if they belong to the same 

 genus. 



The nature and formation of galls on branches 

 and buds is then discussed, and he afterwards takes 

 up the same subject in connection with the Anoma- 

 lies of the Leaf. Referring to galls on the Oak, he 

 observes that in 1815 these trees about Glasgow 

 were much infested by gall-producing insects, and 

 that the galls themselves were frequently as large 

 as a small apple. He notices the galls on the Rose- 

 Willow and the Wild Rose, and states that the 

 Bedeguar of the latter had formerly been much 

 vised in medicine in cases of dysentery, &c. Of 

 another well-known gall he says : " A very singular 

 one may be found on the under surface of the Oak 

 leaf in great abundance in the months of August 

 and September, of a flat shape similar to a button, 

 closely attached to the leaf by a very small foot- 

 stalk, and covered round the edges with fine reddish 

 or brown filaments. This pretty species owes its 

 origin to a whitish worm, so very minute as not to 

 be perceived without the assistance of a glass." On 

 this Sprengel observes that these curious bodies 

 have been called Xyloma pezizoides and Sclerotium 

 fasciculatuin, but he adds that they have been best 

 examined by Hopkirk. 



Hopkirk warns his readers not to attribute all 

 kinds of knots and swellings on stems to insect 

 agency, and refers to thickenings and distortions on 

 the Shepherd's Purse (Capsella Bursa-pastoins) that 

 are due to the stimulus of a parasitic fungus. 



He proceeds to consider the weeping varieties of 

 trees, and is of opinion that while in some cases 

 extreme slenderness or pliability of branch accounts 

 for these, in others, such as the weeping ash, there 

 is a propensity to grow downwards that no care 

 can overcome. He mentions many other variations, 



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