398 CHURCH: DEVELOPMENT OF EMBRYO SAC AND EMBRYO 
after a heavy shower of rain. In contrast it is worth noting that 
Habranthus |Zephyranthes| gracilifolius 8 Boothianus breaks the 
sheath three days before the flower opens (Lindley, 7). .The 
flowering period of Cooperia Drummondii in the vicinity of Austin, 
Texas, usually includes the last week in April and the first week 
in May. 
The material for the study of the development of the embryo 
sac was furnished to the writer by Professor H. H. York, who 
collected it on the campus of the University of Texas. ‘For the 
study of the development of the embryo, bulbs were secured from 
the above mentioned place, and were grown in the greenhouse at 
Brown University. Flemming’s weaker and stronger solutions, 
chromo-acetic acid, alcoholic and aqueous picro-acetic acid were 
used in general for killing and fixation. Aqueous picro-acetic 
gave the best results in the case of the embryo sac and the mature 
embryo. The following additional solutions were tried in an 
attempt to prevent the shrinking of the immature embryo during 
the process of killing and fixation: (1) 2 c.c. of a one per cent. 
aqueous solution of acetic acid, 11 c.c. of a one per cent. aqueous 
solution of osmic acid and 11 c.c. of water for fifteen minutes; (2) 
a one per cent. aqueous solution of osmic acid for fifteen minutes; 
(3) a one per cent. aqueous solution of osmic acid for three min- 
utes, followed by twenty-four hours in Schaffner’s chromo-acetic; 
(4) a solution of osmic acid and acetic acid in the proportions 
mentioned above for three minutes,. followed by Schaffner’s 
chromo-acetic for twenty-four hours; and (5) a two per cent. 
aqueous solution of acetic acid for twenty-four hours. The two 
per cent. aqueous solution of acetic acid proved to be a perfect 
fixing agent for the immature embryos, especially if the individual 
ovules were dissected out from the ovary immediately before 
fixing. Dehydration and imbedding were carried on in the usual 
way, except in the case of embryos large enough to be dissected 
out of the ovule. Here the laying of the material in a certain 
position in order that sectioning might be in the right plane was 
facilitated by staining the embryos in toto by means of a dip into 
erythrosin before dehydration was completed, and the subsequent 
use of the binocular microscope and substage illumination as 
will be described. The binocular microscope was unscrew 
. 
