274 



DEFINITE ACTION OF THE 



Chap. XXIII. 



and he adds that in some seasons certain varieties of this plant all prove 

 good, and the next season all prove bad; whilst exactly the reverse 

 happens with other varieties. In 1845 the editor of the 'Gardener's 

 Chronicle ' 6 remarked how singular it was that this year many Calceolarias 

 tended to assume a tubular form. With Heartsease 7 the blotched sorts do 

 not acquire their proper character until hot weather sets in ; whilst other 

 varieties lose their beautiful marks as soon as this occurs. 



Analogous facts have been observed with leaves: Mr. Beaton asserts 8 

 that he raised at Shrubland, during six years, twenty thousand seedlings 

 from the Punch Pelargonium, and not one had variegated leaves ; but at 

 Surbiton, in Surrey, one-third, or even a greater proportion, of the seed- 

 lings from this same variety were more or less variegated. The soil of 

 another district in Surrey has a strong tendency to cause variegation, as 

 appears from information given me by Sir P. Pollock. Verlot 9 states that 

 the variegated strawberry retains its character as long as grown in a dryish 

 soil, but soon loses it when planted in fresh and humid soil. Mr. Salter, 

 who is well known for his success in cultivating variegated plants, informs 

 me that rows of strawberries were planted in his garden in 1859, in the 

 usual way; and at various distances in one row, several plants simulta- 

 neously became variegated, and what made the case more extraordinary, 

 all were variegated in precisely the same manner. These plants were 

 removed, but during the three succeeding years other plants in the same 

 row became variegated, and in no instance were the plants in any adjoining 

 row affected. 



The chemical qualities, odours, and tissues of plants are often modified 

 by a change which seems to us slight. The Hemlock is said not to yield 

 conicine in Scotland. The root of the Aconitum napellus becomes innocuous 

 in frigid climates. The medicinal properties of the Digitalis are easily 

 affected by culture. The Ehubarb flourishes in England, but does not 

 produce the medicinal substance which makes the plant so valuable in 

 Chinese Tartary. As the Pistacia lentiscus grows abundantly in the South 

 of Prance, the climate must suit it, but it yields no mastic. The Laurus 

 sassafras in Europe loses the odour proper to it in North America. 

 Many similar facts could be given, and they are remarkable because it 

 might have been thought that definite chemical compounds would have 

 been little liable to change either in quality or quantity. 



The wood of the American Locust-tree (Bobinia) when grown in England 

 is nearly worthless, as is that of the Oak-tree w T hen grown at the Cape of 

 Good Hope. 11 Hemp and flax, as I hear from Dr. Falconer, flourish and 

 yield plenty of seed on the plains of India, but their fibres are brittle 



10 



6 « Garcl. Chron.,' 1845, p. 660. 



7 Ibid., 1863, p. 628. 



Dalibert's Experiments, quoted by 

 Beckinan, 'Inventions/ vol. ii. p. 344; 



309. 



8 'Journal of Hort.,' 1861, pp. 64, and Nees, in Ferussac, 'Bull, des Sc. 



Nat.,' 1824, torn. i. p. 60. With respect 

 to the rhubarb, &c, see also ' Gardener's 



1849, p. 355; 1862, p. 



9 ' Des Varietes,' &c., p. 76. 



10 Engel, i Sur les Prop. Medicales 

 des Plantes/ 1860, pp. 10, 25. On 

 changes in the odours of plants, see 



Chronicle,' 

 1123. 



11 Hooker, ' Flora Indica/ p. 32. 



