1848] LIFE HISTORY OF THE PONTEDERIACEA: 337 
Fic. 39. Longitudinal section of an older microspore with generative 
telland tube nucleus. X 1300. 
Fig. 39a. Cross section of microspore of same age as fig. 39. X 1300. 
Fig. 40. Ripe microspore. X 1300. 
Fig. 41. Longitudinal section of ripe microspore, with generative cell 
mid two tube nuclei. X 1300 
Fig. 41a, Cross section of a similar microspore. X 1300. 
Pontederia cordata. 
Fi. 42. Longitudinal section of young. flower; 2, perianth, s, stamen, 
&,carpel. X 125, 
Fig. 43. Ovule before the differentiation of the archesporial cell. X 1300. 
fiG. 43a. Longitudinal section of ovary to show the relation of the ovule 
tothe carpels, 
Fic. 44. Young ovule with archesporial cell. X 1300. 
MiG. 44a. Longitudinal section of ovary to explain fig. 44. 
FIG. 45. Cross section of ovary, semi-diagrammatic; /, vascular bun- 
dles, g, glandular cavities, 
: fig. 46. Young ovule with tapetal cell (¢) and primary sporogenous cel}, 
1300, 
1G, 46. Young ovule. The primary tapetal cell has divided into two. 
*% 1300, 
Fig, 48, Apex of nucellus with four megaspore mother cells. X 825. 
FIGS. 49 and 50. Encroachment of megaspore upon the sterile mother 
aya At this time both integuments have grown beyond the apex of the 
Meellus, x 825. 
FIG. 51, Embryo sac with two nuclei. X 825. 
Fie. 52, Embryo sac with eight nuclei. X 825. 
Pe 53, Embryo sac ready for fertilization. X 825. 
“a 54. Apex of embryo sac with pollen tube. X 1390 : 
“16. 55. Longitudinal section of part of style, showing pollen tube trav 
» @ Cavity lined with glandular cells. X 825. 
_* 56. Longitudinal section of ovary showing ovule, conducting tissue, 
eg tube (A. #.). x 126. 
: — 37-62. Stages in division of microspore mother cell. X 1300- 
2% Chromosomes in equatorial plate of first mitosis of microspore 
cell. x 1300 
Figs, 6 
4 and 65. Matur i 1300 
Fy € microspores. X 1300. : 
oom 6-71. Stages in the early growth of the embryo; 4 dermatogen 
Heteranthera graminis. 
— 
x Fig, 
a Embryo Sac ready for fertilization. X 1300. 
