50 



BOTANY 



of stem and root. The rhizophores of Selaginella (Fig. 54) which 

 have been variously interpreted as leafless shoots, as roots, and as 

 organs sui generis, also find their place here. They resemble leafless 

 shoots, attain a considerable length, and may branch dichotomously 

 and give rise to endogenous roots close to the growing points. As a 

 matter of fact they are in structure and general behaviour inter- 

 mediate between shoot and root, and it is not probable that they 

 have originated from either of these primary members. 



FIG. 53. IKoscorea sinuata. Tuber separated from the shoot ; A, from above : /;. from below. 

 The lower side bears roots. (After K. GOEBEL. A nat. sixc.) 



Various outgrowths of the body of the plant to which an inde- 

 pendent origin is to be ascribed are grouped together as EMERGENCES. 

 A phylogenetic significance cannot be attached to the term as here 

 used. It includes structures of the most different origin belonging 

 both to the thallus and the cormus. The rhizoids, which serve to 

 fasten the thallus of many Thallophytes and the cormus of the 

 cormophytic Bryophyta to the substratum, as well as the massive 

 attaching organs of many Brown Sea-weeds (Fucaceae and Lami- 

 nariaceae) are classed here. So also are the structures which contain 

 the asexual and sexual reproductive cells of the cryptogams (sporangia 



