536 Brown: EMBRYO-SAC AND EMBRYO IN PHASEOLUS 
garden during the summer of 1915. Material was collected from 
the time the buds began to appear until the fruits were fully 
grown. ; 
The very young buds were plated in the fixing fluids intact; 
the floral envelopes were removed from the larger buds and flowers 
to insure penetration of the fixing fluids. For the same reason 
the pods were cut into pieces, and in the case of the older pods the 
young seeds were picked out and placed separately in the fixing 
solutions. Flemming’s solutions, medium and strong; I per 
cent. chrom-acetic acid, Juel’s fluid and Carnoy’s fluid were used 
as fixatives. The best preparations showing the development of 
the macrospores and the embryo-sac were obtained from material 
fixed in Flemming’s medium solution and in chrom-acetic acid. 
Juel’s and Carnoy’s fluids gave best results in the fixation of 
embryos. 
Longitudinal sections of these various structures were cut from 
five to twelve microns in thickness. Flemming’s: triple stain, 
Heidenhain’s iron-alum haematoxylin, and a combination of the 
latter with Lichtgriin were used. 
I have found no differences between any of the varieties used, 
so far as the history of the embryo-sac and the embryo are con- 
cerned; the description which follows applies equally, therefore, 
to all the varieties named. ; 
THE MACROSPORES AND THE EMBRYO-SAC 
In the varieties of Phaseolus vulgaris studied, from two to 
seven ovules are borne in an apparently single row upon the 
adherent edges of the carpel. When first formed the ovules are 
orthotropous, but as growth proceeds they become recurved and 
are campylotropous when mature. 
he two integuments, when fully grown, surround the ovule 
on all sides, but are slightly shorter on the side toward the placenta. 
They grow rapidly and by the time that the macrospore mother 
cell is fully grown the outer integument has reached almost to the 
apex of the ovule, the inner one being at this time about two 
thirds the length of the outer integument. 
A hypodermal cell in the axial row of the nucellus becomes 
larger than the surrounding cells and stands out conspicuously 
