SHOOTS AS POTENTIAL INDIVIDUALS 267 



though the rhizomes are not specially well protected, 

 and often grow slowly throughout the winter. 



The methods of vegetative propagation in the higher 

 plants show that any shoot which has the power of 

 rooting at its base may be regarded as a potential 

 individual. In artificial propagation by means of 

 cuttings, a branch shoot is cut off and the cut end 

 stuck into damp soil. Roots are produced from this 

 surface, and the detached shoot becomes a new plant. 

 This extensive power of producing new individuals 

 vegetatively is a character which separates the highest 

 plants very sharply from the highest animals. The 

 bodies of the latter are very highly integrated, i.e. 

 they form very closely knit wholes, so that none of their 

 parts can Hve independently, while the bodies of plants, 

 with their indefinite growth and number of branches, 

 constantly repeating the structure of the original 

 shoot, and able under suitable conditions to live inde- 

 pendently, do not form nearly such highly integrated 

 individuals. This is largely connected with the fact 

 that the bulk of their bodies is composed of com- 

 paratively undifferentiated living cells which are not 

 so far removed from germ cells as those of the more 

 highly specialised tissues of the higher animals. (Cf. 

 pp. 206-7.) 



PRACTICAL WORK. 



Annual Herbaceous Plant. 



(i) Examine a small herbaceous plant with a single main shoot 

 and a taproot. Make a sketch of the plant showing the following 

 parts : taproot, branch roots, hypocotyl, cotyledons, nodes, internodes, 

 leaves, leaf veins, terminal buds, axillary buds, flowers ox flower buds. 



[Any small quickly developing annual is suitable if it retains 

 its cotyledons till it produces flowers. Chickweed (Siellaria 

 media) or one of the annual Veronicas — V. agrestis, Tournefortii 

 or hedercefolia — does very well.] 



