1914] 



SNOW— DIAPHRAGMS OF WATER PLANTS 



509 



• 



To ascertain if gallic acid was present, fresh sections were 



treated with 



m 



cyanide (Trimble 33). The 



m 



of the sections gave no reaction, but one or two showed a faint 



mass 



sclerenchym 



many 



a very pale brown, thus showing the presence of tannin rather than 

 gallic acid. When the sections, which had been washed after 



Fig. 12. — Scirpiis validus: cross-section of tip of very young stem: two longi- 

 tudinal bundles and connecting cross-bundles {cb)\ the latter runs in a diaphragm (d); 

 cross-bundles connect with phloem (p) ; diaphragm cells starting to form groups; note 

 similarity between cells of diaphragm and of cross-bundles; c, cortical parenchyma; 

 Pr, partition wall separating two spaces; s f cells of space; x, xylem; /, food storage 

 cells; X175. 



the phloroglucin test, were treated with KCN, many cells (pre- 

 sumably those which had responded to the previous test) imme- 

 diately turned dark brown. It is thus seen that after the 

 phloroglucin test the tannin reaction takes place with great 

 rapidity and clearness. 



Since the fresh cells give the tannin reaction with K.,Cr 2 7 and 

 FeCl 3 , and also the phloroglucin reaction, it is possible that the 

 food is stored as some tannin compound containing the phloro- 

 glucin radical. I am not sufficiently familiar with the chemistry 



