1914] 



SNOW— DIAPHRAGMS OF WATER PLANTS 



499 



Til 



or absence of cross-bundles. 



former 



scular diaphragms are men- 

 outnumber the latter that 



some authorities consider the chief function of diaphragms 



the support of the cross-bundles. 



Scirp 



cross-bundles is so nearly universal that the relatively few instances 

 where they cannot be found lead one to suspect that in these 

 cases the material has been broken or a section or two lost at the 

 critical point. 



Fig. 2. — Scirp 11s validus: longitudinal section of very young stem: diaphragm 

 cells elongating to form cross-bundle; nuclei indicate the greater density of proto- 

 plasmic contents of cells of diaphragm and partition walls of spaces; some nuclei were 

 not demonstrable but were placed arbitrarily; p, partition cells; d, diaphragm cells; 

 6, young longitudinal bundle; s, cells of space; c, elongating cells; X175. 



B. OF CROSS-BUNDLES 



Duval Jouve (9) 



Musa p 



disiaca as containing large spiral vessels; those of Butomus umbel- 



lancifolia, and S. sagittifolia 



He 



In 



loins 



bundles of trache 



bundles connect w 



his next paper (9) he describes a cross-bundle as articulating itself 



with the side of the longitudinal bundle, a little back of the large 



vessels and opposite the interior region of tracheids and small 



vessels. A figure in a third paper (10) shows a cross-bundle uniting 



with the phloem. 



