163 



STERILITY FROM THE 



Chap. XVIII 



Variegation seems generally to result from a feeble or atrophied conditio 

 of the plant, and a large proportion of the seedlings raised from parent 1 

 both of which are variegated nsnally perish at an early age ; hence v & 

 may perhaps infer that doubleness, which is the antagonistic state com 6 

 monly arises from a plethoric condition. On the other hand, extremel - 

 poor soil sometimes, though rarely, appears to cause doubleness- I 

 formerly described 97 some completely double, bud-like, flowers produced 

 in large numbers by stunted wild plants of Gentiana amarella growing on 

 a poor chalky bank. I have also noticed a distinct tendency to donbleness 

 in the flowers of a Eanunculus, Horse-chesnut, and Bladder-nut (II 



JEsculus pavia, and Staphyled) 



emu % 



able conditions. Professor Lehman 98 found several wild plants growing 

 near a hot spring with double flowers. With respect to the cause of 

 doubleness, which arises, as we see, under widely different circumstances 

 I shall presently attempt to show that the most probable view is that 

 unnatural conditions first give a tendency to sterility, and that then, on 

 the principle of compensation, as the reproductive organs do not perform 

 their proper functions, they either become developed into petals, or addi- 

 tional petals are formed. This view has lately been supported by Mr. 

 Laxton," who advances the case of some common peas, which, after lon°- 

 continued heavy rain, flowered a second time, and produced double 

 flowers. 



Seedless Fruit .—Many of our most valuable fruits, although consisting 

 in a homological sense of widely different organs, are either quite sterile, 

 or produce extremely few seeds. This is notoriously the case with our 

 best pears, grapes, and figs, with the pine-apple, banana, bread-fruit, 

 pomegranate, azarole, date-palms, and some members of the orange-tribe. 

 Poorer varieties of these same fruits either habitually or occasionally yield 



Most horticulturists look at the great size and anomalous deve- 

 lopment of the fruit as the cause, and sterility as the result; but the 

 opposite view, as we shall presently see, is more probable. 



Sterility from the excessive development of the Organs of Growth or Vegetation. 



Plants which from any cause grow too luxuriantly, and produce leaves, 

 stems, runners, suckers, tubers, bulbs, &c, in excess, sometimes do not 

 flower, or if they flower do not yield seed. To make European vegetables 

 under the hot climate of India yield seed, it is necessary to check their 

 growth ; and, when one-third grown, they are taken up, and their stems and 



seed. 



100 



628. In this article I suggested the 



9 7 < Gardener's Chronicle,' 1843, p. 1816,p.I01-110.Meyen('ReiseumErde,' 



Th. ii. s. 214) states that at Manilla one 

 variety of the banana is full of seeds ; 

 and Chamisso (Hooker's 'Bot. Misc., 



following theory on the doubleness of 

 flowers. 



Quoted by Gartner, ' Bastarder- vol. i. p. 310) describes a variety of the 



zeugung,' s. 567. 



99 'Gardener's Chronicle,' 1866, p 

 901. 



bread-fruit in the Mariana Islands with 

 small fruit, containing seeds which are 

 frequently perfect. Burnes, in his 



100 Lindley, ' Theory of Horticulture,' 'Travels in Bokhara,' remarks on the 



p. 175-179 ; Godron, ' De I'Espece,' torn. pomegranate seeding in Mazenderan, as 



ii. p. 106 ; Pickering, ' Races of Man ; ' a remarkable peculiarity. 

 Galltsio, 'Teoria della Riproduzione,' 





