THE STUDY OF PLANTS IN ANCIENT AND MODERN TIMES. 9 



year lies dormant till the third year, when it too emerges simply as a leaf. This 

 transformation of the leaves, or metamorphosis as Linnasus called it, is, therefore, the 

 result of anticipation; and it was assumed by the Linngean school that the cause of 

 this metamorphosis or hastened development was a local decrease in the quantity 

 of nutriment. The idea was, that in consequence of the limited supply of sap the 

 incipient leaves were not able to attain to the size of foliage-leaves, but remained 



Fig. 1. — Seedlings with Cotyledons and Foliage-leaves. 

 l Cytisus Laburnum. - Koelreuteria paniculata. & Acer platanoides. 



rudimentary, as is the case with many bracts; and further, that the axis was 

 no longer capable of elongating, so that the leaves proceeding from it remained 

 close together, became coherent, and thus formed the calyx. The supporters of this 

 explanation relied particularly on the experience of gardeners, that a plant in good 

 soil with a liberal supply of nutriment is apt to produce leafy shoots rather than 

 flowers; whereas, if the same plant is transferred to a poorer soil, where its food is 

 limited, it develops flowers in abundance. 



But yet a third attempt was made to explain this process of transformation, by 

 the theory that parts which are identical so far as their origin is concerned, subse- 

 quently receive the stamp of distinct foliar organs. The diversity in the develop- 

 ment of parts, originally alike, was supposed to depend on a filtration of the nutrient 



