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 Linnzus called it, is, therefore, the 
result of anticipation; and it was assumed by the Linnzan 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. 
1Cytisus Laburnum. 2 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 
