306 
METHODS IN PLANT HISTOLOGY 
tedious, but every ovule will yield a perfectly median longitudinal 
section of the embryo sac, and there is not the slightest difficulty in 
cutting. When the rays look their best, the embryo sac is ready for 
fertilization, or the pollen tubes may be entering; as the rays begin 
to wither, you will find fertilization or early stages in the embryo and 
endosperm. Sections should be about 10 n thick. 
Fig. 110 .—Lilium philadelphicum: photomicrograph of second mitosis in megaspore mother¬ 
cell—chromo-aceticacid; safranin, gentian-violet, orange. Cramer contrast plate; 4-mm. objective; 
ocular X4; Abb6 condenser camera bellows, 1 meter; yellowish-green filter and also a strong 
filter such as is used in outdoor work; camera bellows, 1 meter; exposure, 7 minutes. Negative 
by Miss Ethel Thomas. X626. 
The Ranunculaceae, especially Anemone patens var. Wolfgang - 
tana , show a rather large, broad embryo sac, with highly organized 
egg apparatus and antipodals. Sections should be 10 to 20 thick. 
For general views of the embryo sac, the safranin, gentian-violet, 
orange combination is recommended. 
