AFFINITIES OF BALANOPHORE^. 11 



the lobes of wliicli project outwards as the bases of the medullary rays ; and between these 

 lobes Lie the axial ends of the vascular wedges. The following is a summary of these 

 characters : — 1. The axis is occupied by hexagonal cells, which become vertically elon- 

 gated and woody {see 2.) towards the vascular wedges, and then radially elongated in the 

 meduUary rays, and pass insensibly into the membranous hexagonal tissue of the cortical 

 portion : these cells contain grains of starch, and chlorophyll in abundance. 2. The 

 woody tubes forming the outer zone of the axis (Avliich is in many respects analogous to 

 a medullary sheath) consist of long and strong cylindrical pleurenchyma, with much- 

 elongated angular sclerogen-ceUs : these are all extremely hard, and their walls are per- 

 forated by innumerable canals. In old specimens the pith passes gradually into these 

 tissues ; its utricles becoming first cubical, with thick dotted or perforated walls ; then 

 becoming tubes elongated vertically ; which are succeeded by tubes with blunt ends and 

 narrow cavities. 3. The wood consists whoUy of scalariform vessels which are cylin- 

 di'ical ia young rliizomes, but polygonal with transversely barred or gashed waUs in older 

 ones ; intermixed in every mstance with smaller, more irregular and variously marked 

 or perforated cells and tubes. 4. The liber-bundles consist of large, stout-waUed, woody, 

 hexagonal tubes, of great density ; their walls everywhere perforated by canals. 5. The 

 isolated sclerogen-cells in the cortical portion in no respect but shortness differ from liber. 



Both in arrangement and in anatomical characters this description of the rhizome re- 

 sembles in most particulars that of the stems of many Menispermece ; and a more close 

 examination bears out this resemblance. 



In a transverse section of the peduncle of Selosis mexicana (Plate XV. fig. 12), eight 

 symmetrically disposed vascular bundles are seen, and outside of these a few smaller 

 irregularly scattered ones : and, as in Balanophora, the anatomical structure of the ves- 

 sels composing these differs from that of the rhizome only in degree. The bundles consist 

 of a sheath of elongated cellular tissue, enclosing a few fusiform vessels, some scalariform, 

 others with spu'al bands or transverse bars, with a few woody tubes and sclerogen-ceUs ; 

 and these may be traced up to the scales of the capitulimi, to which scales much stronger 

 bundles are given off than to the flowers. 



In the rliizome of Selosis gmjanensis (Plate XVI. fig. 30) I find — 1. The whole pith 

 formed of the same woody vessels as surround the pith of S. mexicana ; and this both in 

 New Grenada, Trinidad, and Eio de Janeiro specimens ; these pass into a muriform tissue 

 of woody tabular ceUs, which occupy the broad medullary rays, and of polyhedral cells 

 still wdth very thick walls, in the circumference of the rhizome. 2. The wood is seen in 

 a transverse section to be formed of seven lanceolate wedges of soft, white, scalariform, 

 or spirally unrollable tubes. 3. A very large reniform mass of Uber-ceUs or short tubes 

 is placed outside each wood-bundle, and in contact with it. This does not seem to in- 

 crease annually, but other and equally large hber-bundles form a zone exterior to these, 

 and alternate with them ; as in many MenispermefS. 4. Isolated masses of sclerogen- 

 ceUs and long liber-vessels are scattered throughout the parenchyma of the periphery. 



The peduncle of Selosis ginjanemis presents innumerable bundles of vascular tissue, 

 composed of sclerogen-cells, spnally marked and scalariform vessels, and a few woody tubes, 

 generally occupying definite relative positions. In a specimen of S. guyanensis from 



c2 



