Miyake, The development of the gaiiietophytes etc. 23 



Fig. 39. The same, in spindle of first division ; equatorial-plate stage. 



30. 



Fig. 40. The same, in telophase. X 1330. 



Fig. 41. Functional megaspore with two disorganizing spores above. 



X 660. 



Fig. 42. Outline of longitudinal section of young ovule; megaspore 

 mother-cell in metaphase of first division. Fig. 39 is sketched from the same 

 preparation. \ 50. 



Fig. 43. The same at a later stage; integument is not shown. Female 

 prothallium probably in four-nucleated stage. Tapetum is shaded. X 50. 



Fig. 44. Four-nucleated stage of female gametophyte. X 660. 



Fig. 45. Longitudinal section of ovule slightly older than that offig. 43. 

 Tapetum is shaded. April 30. ; 50. 



Fig. 40. Longitudinal section of central portion of young ovule, showing 

 the arrangement of tapetum-cells around young gametophyte. < 240. 



Fig. 47. A portion of young prothallium whose nuclei are in division. 

 X 660. 



Fig. 48. Longitudinal section of nucellar part of ovule, showing young 

 gametophyte and well-developed tapetum. Tapetum is shaded. X 50. 



Fig. 49. The same, in a later stage. May 17. X 50. 



Fig. 50. The same, in a much later stage. Tapetum, which now consists 

 mostly of a single layer of cells, is not shown. June 8. X 50. 



Fio-. 51. A part of fig. 50 highly magnified, showing a parietal layer of 

 free nuclei, tapetum and nucellar cells. X 660. 



Fig. 52. Surface view of free-nucleated prothallium as shown in fig. 51- 

 X 660. 



Fig. 53. Slightly later stage than in fig. 51; beginning of wall-formation 

 between the nuclei. <, 660. 



Fig. 54. Still later stage. < 660. 



Fig. 55. Surface view of the same. 'A 660. 



Fig. 56. A part ofthebase of mature prothallium, showing the structure 

 of megaspore-membrane at this stage. X 660. 



Plate IM. 



Fig. 57. A part of growing prothallial tissue as it half way advanced 

 toward the center of vacuole. X 160. 



Fig. 58. Solid prothallial tissue just formed. X 50. 

 Fig. 59. Tip of the same more highly magnified. V 160. 

 Archegonial Initials. ,-, 160. 



Upper part of the same more highly magnified. X 660. 

 The same, with dividing nucleus. : 660. 

 Young archegonium with a single primary neck-cell. X 160. 

 Upper part of a similar archegonium, more highly magnified; 

 neck-cell is dividing. ' .~.. 660. 



Fig. 65 a. A little later stage. \ 160. 

 Fig. 65 b. Upper part of the above. ' < 660. 



Figs. 66 — 68. Later stages in the development of archegonia. Fig. 68 

 represents an archegonium which has nearly reached to its füll size. ^\ 160. 



Fig. 69. Upper part of female prothallium, showing a young archegonial 

 complex. ys. 50. 



