260 Dr Christison on the [sess. lu. 



dition iu 1878, Lut since then has greatly degenerated, many 

 branches having died, and the foliage getting thinner every 

 year. This seems to have been brought about l)y the severe 

 seasons 18V9 and 1880, as the girth-increase fell in these 

 years to 0'25 and 0"30 from the substantial yield of 0"70 in 

 1878; a partial recovery took place in 1881 to 0'40, an 

 amount which has never since been exceeded. There was 

 no evidence of depression in 1883 or 1887. Its average rate 

 has been 0"37. 



jEscuIus Mppocastamnii. — This horse chestnut stands at 

 the south-east angle of the original Botanic Garden, in a belt 

 of trees and shrubbeiy, and is considerably crowded and 

 overshadowed by neighbours. In 1878 it increased 0"70, but 

 suffered a considerable diminution in its increase in the two 

 following bad seasons ; in the third, however, it rallied com- 

 pletely. Next year, in conunon with all of its species that 

 I saw in the Edinburgh district, it was the subject of some 

 disease, which completely withered the leaves early in May. 

 Tiie increase that year fell to O'lO, and iu the last six year; 

 has averaged only 0"17. The remarkable fact is, that during 

 this period of profound depression in the girth-increase the 

 foliage, with tlie exception of the lirst year, has been remark- 

 al)ly healthy and dense. So great and sudden a fall can 

 scarcely be attrilnited to increasing pressure from other trees, 

 and most ])r()l)al)ly depends on a prolonged effect of the 

 disease in 1882. 



Jufjlans regia. — The walnut is a ti'ee not often seen in 

 the Edinljurgh di.sti'ict, yet this specimen has grown to a 

 respectable size in a position where it nuist have been 

 openly exposed, for many years at least, to the strong west 

 winds. 



The very short trunk at its narrowest part, about a foot 

 from the ground, measured 1 1 feet 3 inches in girth in 1878, 

 but as it was diniciilt of olKservalion thei'e, the annual 

 measurements were made afterwards on (jue of the two main 

 lindis. Appar(!ntly a slight growth still goes on, averaging 

 0'13 annually in tlic (lcc,(-nnia,l |K'.iio(l ; Imt if 1 lie, measurements 

 over its rough bark are reliahk;, this low anujunt is due to 

 the severe winters of 1880 and 1881, as the liml) appears to 

 have increased by ahout lialf an inch in each of the two 

 preceding year.s. The foliage, in general shabl>y of late years, 



