232 MR. W. ARCHER ON BALLIA CALLITRICHA ЕТС. 
accessory branchlets (the ramification-cells with the change mentioned in text), lower down still 
the branches showing pinne. x 50. 
Fig. 15. A portion of same plant more magnified. Тһе branches have (all but one, which remains 
simple, having formed no ramification-cells) become secondary rachises ; and the ramification- 
cells of the principal rachis have given off cortical cells : these have not yet completely clothed 
the rachis, in fact only on the sides; nor have they given off any lateral branches. In one place 
(fitfully enough) the ramification-cells on each side of a secondary rachis have given off cortical 
cells. The large pits and stoppers of the median rachis are very prominent; they are much smaller 
in the secondary rachises, gradually diminishing in size upwards, smaller still and gradually 
diminishing in the collateral branchlets and pinne, but, though reduced to mere dots, are always 
present. х 50. 
Fig. 16. A small portion, similar to fig. 15, more magnified. х 100. 
Fig. 17. Diagrammatic figure of the first cortical cells. 
Fig. 18. Diagrammatic figure of the commencing growth of the cortical cells from the ramification of the 
** third? (r с") ; “cort. сей 1” indicates the first lateral cell, and “ cort. cell 2” one of the 
frontal cells, which lay the foundation of the cortex, indicated in figs. 15 and 16. 
Piare XXIX. 
Fig. 1. Tuft of Ballia scoparia, of natural size. 
Fig. 2. A portion of a plant, x 50. 
Fig. 3. Diagrammatic figure of the extremity of a branch, showing two spine-like thickened acuminate 
branchlets, the apical cell also spine-like, thickened aud acuminate; the pits and stoppers very 
minute and nearly obsolete. | 
Fig. 4. Mode of branching of cortical cells in this species. 
Fig. 5. Commencement of a branch by the outgrowth of the lateral ramification-cell (r c). 
Fig. 6. A stem or branch with a secondary branch, showing edge view of two ramification-cells (rc, rc). 
Figs. 7, 8. The mode in which the branches appear as if inserted. 
Fig. 9. А ramification-cell (ғ c), seen from the front, showing its elliptic figure (lenticular in edge view, 
see fig. 6) and central pit between it and the parent joint. 
Figs. 10 and 11 show the mode of giving off of the dependent * cortical” cells from the principal stems : 
r с, the ramification-cells ; 2, the septum cutting off the lenticular cell (marked ?), of questionable 
purpose. In fig. ll, at а occurs one of the ultimately numerous branches going to make up 
the confused plexus seen in some specimens. They frequently show here and there the formation 
of the lenticular ramification-cells. It would have been better if fig. 11 had been inverted 
to indicate the dependent direction of these cortical ramifications. 
Fig. 12. Ballia callitricha (typical) : nat. size. 
Fig. 13. A spray of this beautiful plant, х 50, showing its elegant closely set “ plumes.” 
Fig. 14. Showing cortical investment : x 25. 
Fig. 15. Same more highly magnified: x 100. 
Fig. 16. Portion of Ballia Brunonia, of nat. size. : 
Fig. 17. Part of the same specimen, x 50. (Mr. Eaton's plant seems to accord more with this form.) 
Fig. 18. Small portion, still more highly magnified: x 100. 
