CYCADALES 



9 



and tul)Ci-clelike rootlets. The apparently dicliotomons branch- 

 ing of these bodies has led to the general statement that the sec- 

 ondary rofjts of C'ycads 

 branch dichotomously, 

 lint the dichotomy even 

 in this case is only ap- 

 parent, for the true 

 apex, although com- 

 pletely checked in ac- 

 tivity, is evident be- 

 tween the branches. In 

 1872 Reinke « an- 

 nounced the presence of 

 an endophytic alga in 

 these tuberclelike root- 

 lets, which he referred 

 to Ajiabaeiia, an<l in 

 1894 Schneider 1^ pub- 

 lished an account which 

 gave naicli fuller de- 

 tails. From a recent 

 paper by A. (J. Life,^^ the following facts are obtained. 

 It appears that the soil aliout the roots is full of low algal and 



fungous forms, and these 

 forms are found also thickly 

 clothing the roots. At the 

 very inception of a branch 

 bactorioid forms effect an 

 entrance, and are found in 

 aljundance in the cells of the 

 apical region. Presumably 

 through their activity ex- 

 crescent growth begins, and 

 a definite zone of cortical 

 cells is disorganized, result- 

 ing in a cortical chamber 

 about midway in the cortex 

 (Fig. 7). Upon the surface 

 numerous lenticel-like openings are developed, and connect with 

 the cortical chamber, which soon becomes filled with Nostoc 



Via. 6. — The so-called " root tubercles " of Ci/cas 

 rtDoluta\ about natural size. — After Life. 



Fii 7 — I loss section "f i 'i it tubiuk' 

 (\ ( ijia^ ^fiioIuta,s\i< w 111^ tlu il_ il zone, 

 — Uti I Life 



