376 



the monstrous pears have no core. If the proUferous axis of the fruit 

 divides, lateral, smaller pears sprout around the central one. 



In apples, the ability to sprout often extends only to some branches of 

 the vascular bundles in the fruit. Then a knot swells out at the side and 

 can increase to a small secondary fruit. If the lateral sprout develops and 

 produces an actual bud, we find two cores lying diagonally above one 

 another. This case bears great resemblance to double fruits which arise 

 from the union of two separated, laterally placed embryonic flowers. A 

 simple case is the development of a dormant leaf bud on the unthickencd 

 part of the fruit, i. e., the stem. 



In conifers, proliferation is found in the continued growth of the cone 

 axis into a needled branch; this may be found most often in larches (see 



i^'ig- 56). 



Among the phenomena in which an excess of plastic food material is 

 manifest, belongs also the occurrence of leaves at places on the axis which 

 normally should be leafless, Chorisis, and the increase of the leaf organs 

 in a node {Doubling, Dedoublenient) as also the multiphcation of parts of 

 a compound leaf (Pleophylly). The most common example of the last 

 case is the four-leafed clover. Tammes', in a recent study of this case, 

 mentions that De Vries, by continued selection, has created a race, the in- 

 dividuals of which possess four to seven leaves. This is also a very good 

 example of the way in which phenomena of over-nutrition, once produced 

 accidentally, may become hereditary. We referred to this point also in 

 treating of fasciation. In the clover, individual veins and even the mid- 

 rib seem more vigorous and are divided, at times extending even into the 

 petiole. Then each part of the divided petiole bears leaflets at its tip. 

 Pleophylly also deceases on the branches of the second, third and fourth 

 order in which the supply of nutrients decreases in contrast to the first 

 produced, vigorous axes. We find less striking examples in all plants. 

 Leaves which display especially strongly developed leaf surfaces and then 

 a forking of the different veins are found everywhere on the branches 

 most favorably located for the supply of nutrition. 



Such luxuriantly developed forms are found most often in the so-called 

 sprouting of the stock, i. e. sprouts growing from dormant and adventitious 

 buds on the stumps of felled trees (for example, Populus and Morus). 

 The size proportions usually far exceed the average and the leaf forms 

 often vary from the type, even to unrecognizable forms. In these cases the 

 newly produced shoots have the whole store of reserve substance of the 

 tree stump at their disposal, which causes their enormously increased 

 growth. 



As related phenomena we will also name here the witches-broom which 

 we may pronounce a "twig-malady." The accumulation of the plastic food 

 material in various places in the branch, which gradually seeks utilization 



1 Tammes. Tine, Ein Beitrag zur Kenntnis von Trifolium pratense quinquefolium 

 de Vries, Bot. Zeit. 1904, Part XI, p. 211. 



