BUDS ON LEAVES. 45 



germinating are developed without fertilization from the ovules concealed in the 

 ovary. 



The instances of bud-formation above enumerated, when considered with respect 

 to their origin, show that not only cells of roots, but also those of all regions 

 of the stem, and of scale-, foliage- and floral-leaves may become initial cells of 

 buds, or, in other words, of rudimentary shoots. Hence we may draw the 

 conclusion that all the living protoplasts which are capable of division in whatever 

 part of the plant their cells are situated, from the root-tip to the highest apex of 

 the stem, and from the scale-leaves to the ultimate floral-leaves, have the power 

 of undertaking the function of renovation without previously undergoing 

 fertilization. Under ordinary circumstances, no doubt, it is only protoplasts in 

 the cells of the axis, close to the spots where the foliage-leaves emerge, which 

 turn into rudiments of shoots, and the most natural explanation of the selection 

 of these places is that the constructive materials prepared or temporarily deposited 

 in the foliage-leaves may there be turned to account at first hand; but in extra- 

 ordinary circumstances — i.e. as a consequence of unfavourable climatic conditions, 

 or of dangerous injuries, and particularly under the influence of approaching peril 

 of death — the important task of initiating new plants devolves also upon cells 

 situated at most widely difierent parts of the parent stock, cells which otherwise 

 would certainly not have assumed this function. In these cases it is astonishing 

 to see how stress of external circumstances results in ah entirely new division 

 of labour in the cells of the tissue affected thereby; how in one place a protoplast, 

 originally destined to play an altogether different part, divides and becomes 

 the starting-point of a fresh plant, whilst the protoplasts of neighbouring cells 

 convey constructive materials to that particular member of their fraternity and 

 are regularly consumed by it. Very different would have been the order of 

 things and the kind of co-operation of adjoining protoplasts under ordinary 

 conditions! 



