1904] BILLINGS—TILLANDSIA USNEOIDES I21 
Fic.%7. Formation of quadrant 
Fic. 28. Division of middle before terminal segmen 
Fic. 29. Unusually early development of basal and ae segments. 
Fic. 30. An unusual form of embryo. 
Fics. 31-36. Stages in embryo development; in jig. 34, the transverse walls 
in the terminal segment are oblique; the last three figures show beginning of 
dermatogen. 
1G. 37. Embryo about one-fourth grown 
Fics. 38-40. Outlines of embryos in ‘ate stages of development; jig. 30 
represents a mature embryo. 
1G. 41. Region in vicinity of growing point of a nearly ripe embryo. 
Fic. 42. Root region of nary mature embryo, showing dead cortical cells. 
Fic. 43. Ripe see 
Fic. 44. Barbs on ‘die of coma. 
Fic. 45. Early stage in germination; outline of longitudinal section. 
Fics. 46-48. Stages in development of seedling; outline of longitudinal sec- 
tion. 
Fic. 49. Longitudinal section through the growing point regions of a mature 
plant: s, sheath; st, stem; /, leaf; sa, stem apex; Ja, leaf apex. 
Fic. 49a. Very young sheath. 
Fic. 50. Cross section of leaf; p, pit in water-storage cell. 
Fic. 51. Bundle of leaf enlarged to show phloem (p) and xylem (3. 
Fic. 52. Megachloroplasts showing division into microchloroplasts. 
Fic Stage in separation of microchloroplasts by which they become dis- 
inuted through the cytoplasm. 
Fics. 54-61. Stages in development of the scale seen in longitudinal section; 
fig. 54 shows the epidermal cell from which the scale arises. 
Fics. 62-68. Stages in scale development seen from the surface; fig. 68 
shows a mature scale. 
Fic. 69. Scale in longitudinal section, after soaking in water for several 
hours; the wing is seen to be raised considerably above the epidermis. 
1G. 70. Scale in longitudinal section, drawn from a aga section; it will 
be seen to lie much closer to the epidermis than the one in jig. 6 
IG. 71. General appearance of the surface of the leaf, chit ‘the scales. 
Fic. 72. Section through a stoma; the guard cells are unquestionably closed; 
in addition a process has grown up from the parenchyma into the pore of the 
stoma; s, scales 
IG. 73. Section of stoma showing slight variation from that in jig. 72; figs. 
72 and 73 were drawn from sections through living material. 
Fic. 74. Cross section through the vascular et of the stem: ~, phloem; 
x, xylem. 
