1896-97-] THE GAMETOPHYTE OF BOTRYCHRM VIRGINIANUM. 295 



Plate III. 



Fig. 47. — An older embryo ; y, the root ; v, the shoot ; /, foot ; a, initial cell of 

 shoot ; b, initial cell of root. x 250. 



Fig. 48. — A younger, but largfer embryo than the foregoing;, with the same lettering. 

 X 250. 



Fig, 49. — An advanced embryo ; ;-, root ; c, cotyledon ; .v, shoot ; f, foot. x 160. 



Fig. 50. — From a photomicrograph. Lettering as before ; cai, calyptra. This 

 embryo is considerably older than the foregoing. x 50. 



Fig. 51. — Part of a prothallium containing tracheides ; a, decayed spot where an 

 embryo has probably disap]3eared ; t, tracheides. x 250. 



Fig. 52. — Apical region of the shoot in vertical section ; a, the initial cell. x 250. 



Fig. 53. — The same, in horizontal section ; a, the apical cell. x 250. 



Fig. 54. — Longitudinal section of the apex of the cotyledon ; a, apical ceil. x 250. 



Fig. 55. — Apical region of the primary root ; a, apical cell. x 250. 



Fig. 56. — Tranverse section of the same ; a, apical cell. x 250. 



Fig. 57. Transverse section of two united embryos, a and ^. a- is second root of 

 a ; a*, cotyledon of a ; x, central cylinder of « ; b-, second root of b ; b", cotyledon of 

 b ; y, central cylinder oi h. x 50. (From a photomicrograph). 



Fig. 58. — The same, a section through a lower region. Lettering as in the pre- 

 vious figure. (Z^, first root of a ; b''-, first root oi b. x 50. (From a photomicrograph.) 



Fig. 59. — Section through the foot-region of the same embryos. Lettering as 

 before. x 50. (From a photomicrograph.) 



Fig. 60. — Transverse section of a diarchous primary root : a, endodermis ; x 

 xylem ; y, phloem ; b, parenchyma. x 250. 



Plate IV. 



Fig. 61. — Transverse section of the young stem, above the exit of the cotyledonary 

 trace: coL cotyledonary trace; r.c, central cylinder; w, medulla. x 50. (From a 

 photomicrograph). 



Fig. 62. — The same, more highly magnified. x 160. (From a photomicrograph). 



Fig. 63. — Part of the central cylinder of the foregoing, more highly magnified ; en 

 endodermis ; y, phloem ; .r, xylem ; canih, cambium ; .r. /., sieve-tube ; w, medulla. 

 X 220. (From a photomicograph). 



Fig. 64.— Part of central cylinder of quite a young plant ; 01, endodermis ; ph 

 phloem ; cainb, cambium ; x, xylem ; i/i.r. medullary rav. 



Fig. 65.— Longitudinal section of an attached sporophyte ; r, primary root ; x, 

 remains of cotyledon ; /- and /', developing leaves, x 20. (From a photomicrograph). 



