618 Wisconsin Academy of Sciences, Arts , and Letters. 
velopment single ovaries were of necessity used. As far as 
possible the materials were fixed in the field, use being made of 
the simple air pump of the type described by Osterhout (72), 
to insure rapid penetration by the killing solutions. The sec¬ 
tions were cut from five to 25 microns in thickness and stained 
in Flemming’s triple stain and in Heidenhain’s iron liaema- 
toxylin stain,—as well as in Benda’s modification of the iron 
haematoxylin stain. The triple stain was used to the greatest 
advantage on thin sections and the haematoxylin stains gave 
best results on the thicker sections. 
DESCRIPTIONS OF OBSERVATIONS. 
1, The development of the embryo-sac. 
The embryo-sac mother cell of Smilacina racemosa, at the 
time of synapsis, is commonly separated from the outer layer 
of cells of the nucellus by a single cell layer. In some ovules 
more than one cell intervenes between mother-cell and epider¬ 
mis, though in these cases definite layers were not clearly distin¬ 
guishable. Rarely the mother cell seems to lie in contact with 
the epidermis at the time of synapsis. 
In a number of cases more than one mother cell was present 
in the same nucellus and the two were either in contact with 
one another or separated by a thin layer of somatic cells. Two 
cases were observed in which two fully formed embryo'-sacs were 
lying side by side in the same nucellus. In one nucellus the 
embryo-sacs were lying in contact with one another and in the 
other they were separated by a thick layer of sterile cells. This 
latter nucellus was very broad and at the tip showed evidences 
of lobing. 
The first division of the embryo-sac mother cell is in a plane 
approximately at right angles to the long axis of the nucellus 
(Fig. 36). The nuclear phenomena of this division indicate 
clearly that it is the heterotypic division. The short, thick 
bivalent chromosomes which appear in diakinesis, and the pre¬ 
cocious splitting of the daughter chromosomes in the early ana- 
