1910] SAXTON—WIDDRINGTONIA 47 
11. Saxton, W. T., Contributions to the life history of Callitris. To appear in 
Annals of Botany 24:(July) 1910. 
12. STRASBURGER, E., Die Angiospermen und die Gymnospermen. #1. 22. 
Jena. 1879. 
EXPLANATION OF PLATES I-III 
All figures were drawn with Zeiss camera lucida, microscope, and lenses, 
except figs. 39 and 40 (see text). In all: b, ‘“‘brown bodi 
ing cells; d, megaspore mother cells; 
é, functional megaspore mother cell; /, 
male cells; A, integume 
nt; m, nucellus; g, body cell nucleus; #, prothallus; 
r, resin cavity; s, sterile nuclei; ¢, pollen tube; v, vascular bundle. 
PLATE I 
Fic. 1.—Transverse section of mature microsporophyll, showing positions of 
four microsporangia, resin cavity, and vascular bundle. 
Fic. 2.—Transverse section through micropyle of an eve about same age 
as fig. 3; the formation of the ‘“‘wing”’ has only just begun. 
Fic. 3.—Median longitudinal section of a young ovule, ile position of 
megaspore mother cells. 85. 
1G. 4.—Section through megaspore mother cells in an ovule similar to fig. 3. 
X 480. 
Fic. 5.—Two non-functional megaspore mother cells, showing characteristic 
appearance of the “‘brown bodies.”” 825. 
Fic. 6.—Part of nucellus of an ovule slightly older than fig. 3, showing forma- 
tion of schizogenous cavities and sliding growth of three cells. X 205. 
Fics. 7, 9.—Megaspore mother cells in synapsis. 825. 
Fic. 8.—Position of mother cell of fig. 7 in relation to surrounding cells. X 205. 
Fic 
. 10.—Sporogenous cells at a somewhat later stage (see text). 500 
Fic. 11.—Cell 1 of fig. 10. X825. 
Fic. 12.—A functional megaspore and some of the surrounding cells. X 480. 
Fic —A functional megaspore and one of the surrounding cells. 480. 
Fic. 14.—Part of upper cell in fig. 13, more highly magnified. 1150. 
Fic 
15.—A binucleate embryo sac showing disorganization of other sporo- 
genous cells. X 360 
1G. 16.—A four-nuctente embryo sac and the disorganizing mother cells 
surrounding it. 205. 
Fic. 17.—Longitudinal section of nucellus, showing position of pollen tube 
and embryo sac when 64 nuclei are present in the latter; the region occupied by 
disorganizing spore mother cells is shaded. X 35. 
PLATE I 
1G. 18.—Some prothallus nuclei in tangential section of the sac, showing the 
hollow puceait X 825. 
Fics. 19-21.—Three dividing nuclei in the “alveoli.” 1240. 
