346 STRUCTURE AND LIFE HISTORIES 
production there is interposed the enlargement or growth 
of the parent. 
317. Vegetative Multiplication. Attention has also 
been called to the various methods by which the number 
of individual plants is increased by the separation of multi- 
FIG. 252. Branch of a willow (Salix sp.), showing the formation of 
fibrous roots. The lower portion of the stem was placed in water for a 
few days. 
cellular portions of the body of the parent. The most 
familiar of these processes being the artificial propagation 
of plants by means of cuttings. A portion of stem (Figs. 
3 and 252), or sometimes of leaf (Fig. 253), stuck into 
moist sand will form new roots and ultimately develop an 
