1914] 



SNOW— DIAPHRAGMS OF WATER PLANTS 



5 



01 



some 



combined 



surrounding tissue and the " pressure of the secreted air." That 

 the growth of the surrounding tissue causes a pulling out of the 



diminishing 



He 



arms, after having been formed, increase in size (nresum 



growth). 



■j 



(7) considers that the body of the cell 



arms 



x 



grow out as rays; the 

 presence of apparently bifurcated rays indicates a pulling out of 

 the body. In another 

 paper (10) he speaks of 

 the pulling out of the 

 cells from the points 

 of contact. Schwen- 

 dener (30) believes 

 stellate cells to be due, 

 not directly to a pull, 

 but to growth under a 

 tension caused by the 

 faster growth of the 



surrounding tissue. 

 DeBary (6) speaks of 

 cells growing into long 



Fig. 4. — Scirpus validus: longitudinal section 

 arms. Le BLANC (17) of stem: cross-bundle curving, part in cross-section 



(x) and part in longitudinal section; xylem making 

 connection with xylem of longitudinal bundle (b); 



Xi75. 



gives the same expla- 

 nation as Leitgeb 

 (whose paper he has 

 apparently not seen) , and proves the existence of tension in stellate 

 tissue by an experiment. By bursting one of the stellate cells in 



ragm 



& 



than the original cell, and which was caused by a retraction of the 

 surrounding cells. 



formation 



spaces otherwise than by the pressure of the secreted air. Tschirch 

 (34) thinks that intercellular spaces are formed by a splitting of 



primary membrane 



same reaction as the primary memb 



Goebel 



