204 ALTERATION OF POSITION. 



on the direction of branches, thus Dr. Falconer, as 

 quoted by Darwin,^ relates that in the hotter parts of 

 India " the English Ribston-pippin apple, a Himalayan 

 oak, a Prunus and a Pjtus all assume a fastigiate or 

 pyramidal habit, and this fact is the more interesting 

 as a Chinese tropical species of Pyrus naturally has this 

 habit of growth. Nevertheless many of the fastigiate 

 varieties seen in gardens have originated in this country 

 by variation of seeds or buds. 



M. Carriere has also recorded a curious circumstance 

 with reference to the fastigiate variety of the false 

 acacia liohinta pseudacacia ; he states that if a cutting 

 or a graft be taken from the upper poi'tion of the tree, 

 the fastigiate habit will be reproduced, and the branches 

 will be furrowed and covered with short prickles ; but if 

 the plant be multiplied by detaching portions of the root- 

 stock, then instead of getting a pyramidal tree with erect 

 branches, a spreading bushy shrub is produced, with 

 more or less horizontal, cyhndrical branches, destitute 

 of prickles.^ 



Eversion of the axis. In the case of the fig, the peculiar 

 inflorescence is usually explained on the supposition 

 that the termination of the axis becomes concave, 

 during growth, bearing the true flowers in the hollow 

 thus formed. The cavity in this case would probably 

 be due not to any real process of excavation, but 

 to a disproportionate growth of the outer as contrasted 

 with the central parts of the fig. Some species of 

 Sempervivum have a similar mode of growth, so that 

 ultimately a kind of tube is formed, lined by the leaves, 

 the central and innermost being the youngest. The 

 hip of the Rose may be explained in a similar manner 

 by the greater proportionate growth of the outer as 

 contrasted with the central portions of the apex of the 

 flower-stalk. In cases of median prolification, already 

 referred to, the process is reversed, the central portions 



' 'Variation of Animals and Plants,' ii, p. 277. 

 * Quoted in ' Gard. Chron.,' 1867, p. 65i. 



