the Genus Hottonia . 
267 
EXPLANATION OF PLATES XX AND XXL 
Illustrating Miss Prank erd’s Paper on the genus Hottonia. 
The photographs were taken with a Gordon’s Photomicro -camera, and Figs. 18-21 drawn with 
the Abbe camera. All figures and photographs except 2 and 3 are from H. palustris. The follow- 
ing abbreviations are used p. — pith ; p.cav. — pith cavity ; x. = xylem ; p.x. — protoxylem ; 
int.x. = internal xylem ; ph. = phloem ; int.ph. — internal phloem ; v.b. = vascular bundle ; pc. — peri- 
cycle; en. = endodermis ; int. en.= internal endodermis ; ext. en. = external end odermis; cor. — cortex; 
cor.l. = cortical lacuna ; ep. — epidermis ; g. — glandular hair ; ste. = stele ; rt. — root ; int.rt. = in- 
ternal root ; br. == branch ; br.gp. — branch gap ; Ur. = leaf-trace ; l.gp. = leaf-gap ; t.s. = transverse 
section. 
PLATE XX. 
Fig. 1. Part of transverse section across internode of inflorescence axis, x 40. Cf. Diag. 6, 
p. 256, and Fig. 20. 
Fig. 2. Transverse section of a complete stele at base of lateral inflorescence axis of H. infiata. 
x 40. Cf. Text-fig. 5, ste. The arrow shows the direction of the centre of the stem for Figs. 2 and 3. 
Fig. 3. Transverse section of part of stele at base of main inflorescence of H. infiata, showing 
two internal strands with reversed orientation, x 40. Cf. Diag. 4, p. 256. 
Fig. 4. Transverse section of base of inflorescence, showing three incomplete steles, x 11. 
Fig. 5. Transverse section a little lower than Fig. 4 to show complete type of leaf-gap. The 
pith is in direct communication with the cortex through the gap, which is lined by the fused internal 
and external endodermis. x 18. 
Fig. 6. A very little lower than Fig. 5. Shows union of leaf-trace with vascular ring and a root 
springing from the internal pericycle. x 18. 
Fig. 7. Transverse section lower down to show internal thickened ring and incomplete 
leaf-gap. x 18. 
Fig. 8. Part of stele to show transitional type of leaf-gap where the internal endodermis runs 
out towards the external, x 38. 
Fig. 9. Transverse section of aquatic stem about 3 cm. below the base of the inflorescence to 
show contracted internal ring, x 52. 
Fig. 10. About 2 cm. lower than Fig. 9. C = central core of thickened lignified cells, x 38. 
Fig. 11. Considerably lower down. C' = the core of Fig. 10 reduced to a single element, x 52. 
Fig. 12. Transverse section of subterranean stem, showing several layers of cortical cells grouped 
regularly round the endodermis. x 40. 
Fig. 13. Transverse section across a node of the inflorescence axis to show branch gap and 
starch sheath ( st.sh.] ). x 18. 
Fig. 14. Part of a section similar to Fig. 13 on a larger scale to show the internal starch 
sheath (st'.sh'.) which fuses with the external at the gap. Note the contrast of the statoplast with 
the ordinary trophic starch scattered over the ground tissue, x 40. 
Fig. 15. Transverse section of stele just below the transitional region from aerial to aquatic 
type to show the whole of the ground tissue, pith, and cortex as statocyte tissue, x 18. 
PLATE XXL 
Fig. 16 a-e. Three seedlings, x circa d = young plant (natural size) ; cot. — cotyledon ; 
pr.rt. = primary root; adv.rt. — adventitious root. 
Fig. 17. Diagrammatic median longitudinal section through a seedling to show plane of 
section of Fig. 18. Hyp . — hypocotyl. 
Fig. 18. Transverse section of tips of cotyledons (C.) enclosed in disorganized remains of seed 
coat (S.). Ct. = cutinized walls ; N.p. — nucleated protoplasm from cells of inner layer of seed coat 
(int.). x 130. 
Fig. 19 a-e. Serial transverse sections through the wood at the base of a cotyledon (a) passing 
to hypocotyl (e). The arrow indicates the direction of the centre of the stem, x 650. 
Fig. 20. Transverse section of small part of inflorescence axis to show detailed structure 
of bundle, x 70. 
Fig. 21. Transverse section of stem of young plant (d, Fig. 16). x 130. 
