

FUNGOUS ROOT-TUBERCLES. 71 



multinucleated cells in the tubercles of 



ami 





totically when thus stimulated by an infecting fungus, but 

 no such condition is apparent in Ceanothus. It should also 

 be noted that some cells not directly connected with infected 

 ones have but little protoplasmic content. Either the fungus 

 robs the adjacent cells in some unknown way, or else the in- 

 fected cells obtain the lion's share of food supplied by the 

 plant and finally starve the other and smaller cells. 



As the host cell increases in size the nucleocytoplasmic re- 

 lationship is maintained and therefore the nucleus increases 

 with the cell, becoming enormously large compared with the 

 nucleus of an uninfected cell. The average diameter of a 

 normal nucleus is about 5.6/^ whereas the hypertrophied 

 nuclei are usually oblong, measuring 14x21/x. Some pecu- 

 liar and amoeba-like nuclei are shown in f. 8, many of which 

 are quite similar to those in Podocarpus which Shibata (37) 

 found dividing directly. Even the nucleolus increases its 

 size in relation to the nucleus and in some instances seems 

 even to exceed its natural proportion. The amount of chro- 

 matin also increases and it stains a deep color with gentian 

 violet. Passing farther toward the base of the tubercle, the 

 cell and its contents become hypertrophied to the highest 

 degree. In cross section the large infected cells are arranged 

 radially (f. 1), showing in a longitudinal view a more 

 isodiametric form. Those of the transverse section measure 

 60 X 113/a, whereas those of a longitudinal tangential sec- 

 tion are about 50-Q0fi in diameter. Concurrently with the 

 growth of the cell the mycelium becomes more and more en- 

 twined, branching and frequently broken in many places. 

 The mvcelial threads now become much finer and the small 



*• 



nuclei are distributed throughout the length (f. 4, 5, 6). 



mass ot m 



must be made 



next following stage in which the pear-shaped vesicles are 



formed 



This is 



definite 



section where it stains deeply with gentian violet and very 

 dark with haematoxylin, a fact indicating that there is pres- 



