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UA! DES, Vine r X CN A y- TARRE E o AL i "TOR en ae ee 
A EUROPEAN PETRIFACTION WITH FOLIAGE. 491 
I found no evidence of any transfusion tissue between the bundles or in the 
mesophyll. 
The vascular bundles are surrounded by a definite sheath (5.) of two or three 
layers of thickened cells. This sheath is more noticeably thickened on the 
under side in the bundles near the edges of the leaflets. The more median 
bundles, and those in the middle regions of the pinnules have more delicate 
sheaths. A support of sclerenchyma two or three cells thick definitely 
connects the sheath with the upper hypoderm. As the sheath-walls were 
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Details of leaf anatomy. See p. 496. 
considerably thickened presumably they were pitted, but I have not been 
able to determine any definite transfusion-like differentiation. 
The bundle is entirely centripetal, and appears to consist of two or three 
larger vessels and a group of protoxylems : though no bundle is perfectly 
preserved, several show the small wood group lying in place directly inside 
the sheath so that the quantity of wood was evidently small, and soft tissue, 
presumably cambium and phloem, occupies most of the rather large bundle 
space, though the greater part of this soft tissue has disintegrated. - 
The lower epidermis (L. e.) lies but one or two cells distantifrom the lower side 
