178 EMBRYO BUDS. UOVOLI. [BOOK i. 



the wood of the nodule becomes adherent to the wood of the 

 tree. This adhesion sometimes does not take place for 

 several years. The wood of the nodules is arranged in con- 

 centric zones around a common centre, and has both pith 

 and medullary rays; and, however irregular, the form is 

 evidently in all cases a genuine sphere ; it has all the elements 

 of organisation found in the trunk of the tree, but arranged 

 differently." The side next the wood of the parent tree is 

 thicker than the opposite side, which Dutrochet attributes to 

 its being more immediately in contact with the cambium 

 which nourishes it. In the Cedar of Lebanon the nodules 

 have been seen producing a small branch from the summit. 

 M. Dutrochet regards these nodules as adventitious buds 

 arrested in their formation, and he compares them to the 

 internode of Tamus communis, which forms a tuberous root- 

 like body in that species. 



A circumstance to which this physiologist attaches great 

 importance is, that these nodules have an abundance of 

 cambium in the spring, and yet they are not, he says, in 

 communication with the alburnum of the tree ; whence he 

 concludes that cambium is elaborated by the bark exclusively. 

 I am not, however, able to reconcile this statement (Memoires, 

 i. 311.) with another (p. 304.), that the base of the nodule is 

 " certainement" in adhesion with the wood of the tree. 



To me it appears that embryo-buds may be best compared 

 to such woody forms of the growing point as occur in spines, 

 the difference being that spines are developed freely in the 

 air, and embryo-buds under pressure within the bark. That 

 they are really of the nature of buds is proved, not only by 

 the Cedar of Lebanon above referred to, but by their being 

 employed, in the case of the Olive Tree, for the purpose of 

 propagation under the name of Uovoli. I moreover possess 

 some highly singular forms, brought from Prince of Wales's 

 Island, in which they have acquired a very large size, some 

 of the smaller being as big as the human head, in which all 

 sorts of transitions are observable ; some forming spheroidal 

 simple masses, others subdividing, as if about to become 

 branches, and others actually extended into shapeless gouty 

 arms, without, however, producing leaves. 



