Holm, Some new anatomical characters for certain Gramineae. 109 



the effects of concentrated sulphuric acid, and inasmuch as the 

 cell-walls sijow distinct iutercellular Spaces, the conclusion is that 

 it does not represent a mestomesheath, but only some layers of 

 mestome-parenchyma. 



These species of the plumose-awned ^Arihraiherum'^ thus 

 possess only one parenchyma - sheath around the mestome- 

 bundles, and are thus quite distinct anatomically from the others, 

 described above. 



If we consider the other parts of the leaf for instance of 

 Ä. plumosa L., we find the leaf much thicker than in any of the 

 other species already examined, and the blade is strongly condu- 

 plicate without power to open. Both faces of the leaf, especially 

 the Upper, are furrowed, and the furrows are almost completely 

 covered by overlapping, long, pointed hairs as well as by papillae 

 with globular heads, very much resembling glandulär hairs. These 

 papillae were noticed only on the upper surface, while the furrows 

 on the lower face were only covered by rather short, pointed 

 hairs. The stoniata are located in the furrows, and no buUiform 

 cells are developed, The stereome occurs in large groups above 

 and below the mestome-bundles, and is generally much better 

 represented in this species, than we have seen in any of the other 

 sections described above. 



Between the ribs are narrow layers of colorless tissue, the 

 function of which is evidently to störe water, and the same tissue 

 with exactly the same disposition was also, as we remember, 

 observable in the many species of Chaetaria and other sections. 

 We have, already, mentioned the mesophyll as bordering on a 

 parenchyma-sheath, besides that inner layers of thick-walled 

 mestome-parenchyma may, sometimes, Imitate a mestome sheath ; 

 we might State, furthermore, that the parenchyma-sheath is not 

 continuous in the largest bundles, but plainly iuterrupted by the 

 stereome. This condition certainly exists although disputed by 

 Professor S c h w e n d e n e r , but we must concede that it is not 

 usual. To prove it we have carefully treated the sections with 

 concentrated sulphuric acid. 



A corresponding structure is also to be observed in A. acuti- 

 ßora Tr. et Rupr. (Algiers), A. hrachyathera Coss. et ßalb. 

 (Algiers), A. ciliata Desf. (Tunis), A. pungens Desf. v^ar. pennata 

 Trautv. (Russia) and A. pennata Trin. {turkomannia), all of this 

 same section „Arthratherum"' , with only a few unimportant depar- 

 tures. The funows may, for example, be wider and more shallow 

 €n the Upper face, thus leaving space for the development of 

 typical bulliform cells, and very obvious in A. pungens var. pen- 

 nata. Furthermore the mestome-bundles may not be confined to 

 the prominent ribs, but may also be located in the Spaces 

 between these, beneath the bulliform cells and the adjoining broad 

 layers of colorless tissue. But otherwise the structure is very 

 much the same, and the parenchyma-sheath is equally large-celled 

 and thin walled in these species with no signs of a secondary one 

 inside. 



