306 TRANSFORMATIONS OP TOE ENTIRE FLOWER. 



line, in which the different parts of the flowers are inserted round 

 the axis, then becomes very evident. This is not unfrequently 

 the case in the Double Tulip, as well as in some Euphorbiums 

 (Spurges); and as the parts of the flower are generally at the 

 same time more or less changed into the leafy character, the 

 resemblance of the whole flower to a leaf-bud or undeveloped 

 branch then becomes very obvious. Sometimes after giving off 

 the whorls of the perianth, the flower-stalk is prolonged through 

 their centre, and bears another bud at its extremity; this is by 

 no means uncommon in Roses. It is well known to Gardeners 

 that, by a still further change, flower-buds may be actually 

 converted into leaf-buds, and developed into true leaf-bearing 

 branches ; a fact which sufficiently proves, that every part of the 

 flower is formed out of the same elements with leaves, and that 

 the development of either may take place according to circum- 

 stances. Hence we know why a difference in the amount of 

 nutrition which the plant receives, should influence its tendency 

 to the production of flowers and fruit. It has been stated that, 

 in each of the parts of the flower, there is a tendency to revert 

 to the leafy form ; and this is especially the case with the stamens, 

 which are often converted into petals (thus changing a single 

 flower into a double one), when the plant is transferred from the 

 poor soil, in which it may be naturally growing, into the rich 

 mould of a garden. Now if a plant be over-supplied with 

 nourishment, it will run to leaf, as it is termed, that is, it will 

 develope too many leaf-buds, and will not put forth flowers ; so 

 that, in order to make it bear fruit, it is necessary to diminish its 

 quantity of sap ; one method of effecting which, is to dig a trench 

 at a certain distance round the bottom of the trunk, so as to cut 

 off part of the supply it receives from the roots. 



469. It might be objected to the statements here made, that 

 the pollen and the ovules are so different from anything which 

 the leaf naturally produces, that no analogy can be imagined 

 between organs bearing these, and the ordinary leaves. But, if 

 the structure of the pollen-grain be considered, it will be per- 

 eeived to correspond precisely with that of other cells of cellular 

 tissue ; differing chiefly in its power of separating itself from the 



