T. Holm — Anemiopsis Calif omica. 79 



cortical parenchyma, at least the peripheral strata, contains 

 chlorophyll, and is very open from the great width of the inter- 

 cellular spaces ; secreting cells occur, also, here, but are not 

 very frequent. Separating the cortex from a central group of 

 parenchymatic tissue, a pith, is a circle of twelve collateral 

 mestome-bundles, each with a thin-walled parenchyma-sheath, 

 and surrounded besides by strata of stereomatic tissue. The 

 stereome, however, is confined to the periphery of the mestome- 

 bundles themselves, and does not connect these as a continuous 

 ring of mechanical tissue as is the case with the stem. Char- 

 acteristic of the mestome-bundles in the petiole is their ellipti- 

 cal outline in cross-section with the leptome, forming a narrow, 

 linear group in contrast to the broad group of hadrome with 

 numerous, narrow vessels. 



The prophylla. 



As already mentioned, the stolons and flower-bearing stems 

 are axillary ; they bear at their base two scale-like, membra- 

 naceous fore-leaves, the structure of which is as follows : The 

 cuticle is very distinctly wrinkled on the outer, the dorsal face, 

 but smooth on the inner, the ventral. Epidermis is thin-walled 

 and consists of relatively small cells throughout with neither 

 trichomes or stomata ; the outermost portion of the margins is 

 merely composed of epidermis in two layers corresponding to 

 the dorsal and the ventral. The mesophyll is very poorly 

 represented except in the sharp keel ; it is quite open and does 

 not contain chlorophyll, neither is it differentiated as a palisade 

 or pneumatic tissue, but constitutes a homogeneous tissue of 

 roundish, thin-walled cells. There is only one mestome-bun- 

 dle, which is located in the keel ; it has a support of two or 

 three layers of slightly thickened stereome and contains mostly 

 leptome. 



The involucre. 



The involucral leaves at the base of the inflorescence are 

 very conspicuous, being large and white ; they are prominently 

 papillose on the ventral face, each epidermal cell being 

 extended into an obtuse papilla, while the dorsal face is per- 

 fectly smooth. Stomata and secreting cells occur in the dorsal 

 epidermis. A hypoderm of large, roundish cells is developed 

 underneath the epidermis on both faces of the involucre. The 

 mesophyll is almost destitute of chlorophyll ; it is homogeneous 

 and traversed by wide, intercellular spaces, besides by several 

 very small mestome-bundles. 



The floral bracts. 



The cuticle and the epidermis exhibit exactly the same struc- 

 ture as observed in the involucre, while the hypoderm is absent 



