MacDougal : Symbiosis and Saprophytism 525 



stances does the presence of the fungus affect the nucleus. Ex- 

 cretions from the hyphac cause some distortion of a few nuclei, 

 which are also hyperchromatic. The hyphae may be traced around 

 the cell in several circuits. Penetration of the wall and entrance 

 into a neighboring cell is not made until the supply of starch is 

 nearly exhausted, and the solution in the contiguous cell would 

 form a stronger chemotropic stimulus. The portion of the hypha 

 in the wall appears but half the normal diameter of the typical fila- 

 ment, and is nearly colorless even in old formations. 



The ascending rhizome 



The ascending rhizome consists of four or five napiform seg- 

 ments, each consisting of two or three internodes and representing 

 one season's growth. As each segment is formed it gives rise to 

 an inflorescence from an apical node. Later in the season it forms 

 offsets which reproduce the premorse rhizomes with their coral- 

 loid branches. As a consequence of this mode of growth, a dozen 

 plants may be found adherent in a colony, with the coralloid ni}'- 

 corhizas closely crowded in a huge clump. 



The epidermis of the rhizome consists of very irregular ele- 

 ments, some of which contain starch at all times. Numerous 

 hyathodes with a central oval or oblong central cell filled with a 

 dense mass of yellowish brown secretion, surrounded by six or 

 seven radially arranged elements are to be seen (Plate 368, Fig. 

 4). The cortex shows a very copious development, consisting of 

 ovoid or globoid elements with ample air-spaces, and embracing a 

 large number of mucilage cells. This member is therefore fur- 

 nished with a very efficient mechanism for the extrusion of water : 

 an important provision in an organ devoted to the condensation 

 of carbohydrates of soluble carbohydrates to starch, and this pro- 

 cess may continue irrespective of the presence of the aerial shoot. 

 The peri cycle forms a dense heavy ring of 7 to 10 layers rich in 

 proteids. The stele in general exhibits a degree of degeneration 

 corresponding with that of the coralloid branches. Its parenchy- 

 matous elements as well as the cortex are loaded with starch. 



The Inflorescence axis 

 The epidermis consists of flattened cylindrical cells with oblique 

 ends, are rich in protoplasm, and entirely devoid of stomatal open- 



