NOSTOC. 543 



the slime-canal into the gland itself, and there occupy the 

 space left by the glandular cells on their conversion into slime. 

 Thence the filaments find their way into the intercellular spaces 

 of the starch-containing parenchyma surrounding the gland, and 

 become closely applied to the cell-walls. The Nostoc then Ijores 

 through or dissolves the cell- wall, absorbs the starch, and grows 

 vigorously till it fills the whole cell. In this manner the 

 Nostoc spreads through the cortical parenchyma of the Gunnera 

 stem from cell to cell. The stem glands in course of time 

 become inactive and the canal closes up, so tliat the Nostoc is 



Fig. Z-ll.—Anabacna fi/radearum. A, Coml-like surface-roots of Ci/can. li, Tniiis- 

 verse and longitudinal sections of A ; the double line indicates the distribution 

 of the Aox^oo. (V. Tubenf del.) 



completely siiut in. In this condition it is absululcly de- 

 pendent on nourishment derived from the host-cells, and seems 

 to thrive on it. Xo outward symptoms of disease can be 

 observed on Giamera with enclosed Nostoc, the local destruction 

 of the cell-contents, the loss of starch, and the filling up of 

 the tissues with filaments of Nostoc having apparently n<» 

 effect. The species of Gunnera have a very short stem with 

 a growing point hardly raised above the level of the soil, so 

 that the Nostoc easily finds its way there. Xo algae have 

 been found in the petiole and lamina of the gigantic leaves. 

 Gunnera may easily be cultivati'd although it contains no 

 Nostoc. 



Jonsson ^ regards Nostoc f/unncrrn- as identical with ,\'. jmncti- 



'.Jonsson, Botnu. Xofiscr, 1894. 



