CAUSES OF BARRENNESS, &C. 167 



the history of the Andna. T. A. Knight, Esq., in 

 one of his papers presented to the Horticultural 

 Society, asserts, that the effects of very dry or very 

 cold air will " cause even the scions from their roots 

 to rise from the soil with an embryo pine apple upon 

 the head of each, and every plant to show fruit in a 

 very short time, whatever were its state or age." 

 Now this shows decidedly that the whole organisa- 

 tion of the plant is complete from the first, and, by 

 checking the growth of the exterior, the central 

 part, hearing the fruit, comes forth prematurely ; 

 but which could not be the case did the formation 

 of the fruit depend entirely on the quantity of sap 

 " thrown down " by the leaves. 



Annual plants run to seed sooner or later accord- 

 ing as the soil they grow in is rich or poor. On a 

 dry gravelly soil plants are diminutive and preco- 

 cious ; on rich fertile land they are exuberant and 

 late : because the growth of the stem and leaves, 

 deriving a full supply of nutriment, are enlarged to 

 their utmost volume, and of course delay the develop- 

 ment of the flowers and seed. Here it may be added, 

 that the difference in the magnitude of plants of the 

 same kind is not so much caused by a diminution of 

 the number of their parts, but by the diminished bulk 

 of each of them. 



From the whole of the foregoing observations it 

 is sufficiently manifest that every different part of a 

 plant has original existence. From the moment it 

 begins its career of growth all its parts are in a course 



