CYCADACEAE 



93 



Fig. 62. Encephalartos Altensteinii Lehm. I. One half of a transverse section of a 

 °. cone, showing 3 complete scales with two fully developed ovules each, and 

 2 ovules from partly hidden scales. Seen from below. \ nat. size. 2. Transverse 

 section of <-f cone of E. Lehmanni Lehm., seen from below. \ nat. size. 3. Long, 

 section through apex of ovule (facing the axis). 3/1. 4. Portion of Fig. 3. 10/1. 

 m. Micropyle. mt. Micropylar tube. p. Pollen grains (germinating), pt. Pollen 

 tubes (haustoria). pc. Pollen chamber, ad. Archegonial depression, nu. Nucellar 

 tissue.' pr. Prothallial tissue (endosperm), a. Archegonia. 0. Oosphere. 5. Pollen 

 tube, as seen embedded in the nucellar tissue, pg. Germinating pollen grain. 

 gn. Generative nucleus, vn. Vegetative nucleus, a. Growing apex. The two 

 dotted lines indicate the walls of the pollen chamber. 300/1. 6. Transverse section 

 through branch of apo-geotropic root. 5/1. co. Cortex. No. Green layer, 

 containing the alga (Nostoc). m. Medulla. 7. Portion of Fig. 6, enlarged. 25/1. 

 pe. Periderm (cork), the outer layers decayed, co. Cortical parenchyma. No. Layer 

 with Nostoc (the colourless parts are the cells), m. Medulla (pith). 8. Transverse 

 section of leaf. 20/1. sc. Sclerenchyma. pa. Palisade cells (green parenchyma). 

 fb. Fibrovascular bundles, st. Stoma. 9. Portion of under side of Fig. 8. 240/1. 

 (Figs. 3-5 from sketches by W. T. Saxton.) 



