106 ANATOMY AND PHYSIOLOGy OF 



of a cellular mass in its interior, or v/hetlier a complete group of cells 

 must co-operate fiom the very beginning for the formation of the 

 bud, we shall not be able to decide until we shall have traced back 

 the normal development of buds to their first origin. If, however, 

 it should be the case that the formation of a bud starts originally 

 from a single cell, this is still incapable, in the higher plants, of 

 forming a bud, when it is separated from the rest of the plant be- 

 fore it has produced a new individual and this has grown up to a 

 certain point of development, at the expense of nutriment pioduced 

 by other cells. Therefore in all the more highly organized plants 

 only organs of considerable size, composed of numerous cells and 

 containing a certain amount of assimilated nutriment, are capable 

 of laying down the foundation of a new plant. 



I have explained above, the doctrine that a branched plant is 

 composed of as many individuals as it possesses ramifications. 

 Taken stiictly, tins is not absolutely true, for a perfect plant pos- 

 sesses not only an ascending axis, clothed with leaves, but a de- 

 scending axis, a root. In many plants (in all leafy Cryptogamia, 

 and in the Monocotyledons), even the primary axis is imperfect, 

 for merely the ascending portion of it exists, while a primary 

 descending axis is wanting, and is replaced by secondary axes 

 which shoot out firom the lateral surfaces of the stem. The same 

 incompleteness exists in every branch, it consists merely of an 

 ascending axis, therefore corresponds simply to half a plant, as also 

 each ramification of the root represents the corresponding half of 

 a complete plant. 



Since, however, the individual parts of a plant very generally 

 possess the power of producing that part of a complete plant in 

 which they are deficient, when either a sufficient supply of nutri- 

 ment has been stored up in their interier to last, or the requisite 

 sustenance is still conveyed to them by the parent plant, until the 

 completion is attained and they can prepare their own food inde- 

 pendently, there exists, as a rule, little difficulty in producing 

 a new individual furnished with all necessary organs, from a single 

 part of a '|)lant. This is most readily effected with an ascending 

 axis, since, on the whole, this is very prone to pioduce radical 

 fibres from its lateral surfaces, and thus to become placed in a con- 

 dition to sustain itself independently. It is more difficult to raise 

 a new plant from a detached descending axis, since such a root is 

 obliged to produce a leaf-bud, fi^om which the future stem has to 

 grow up ; a reproduction which in general is much less readily 

 effected than the formation of lateral roots fi^om an ascending axis. 

 Finally even a detached leaf may give origin to the formation of 

 a new plant ; in this case it must form both root and leaf-bud, 

 to which, generally speaking, the leaves have but very slight 

 tendency. 



The readiness with which both descending and ascending axes 

 aie formed at places where they do not make their appearance in 



