374 BOTANICAL GAZETTE [May 
zation in normal material, and before the division of the egg in 
parthenogenetic material. 
3. Fertilization is not necessary to embryo-development or 
to endosperm-development. 
4. Embryos were produced parthenogenetically under all a 
conditions, and normal material showed the phenomenon tobe 
general in nature. 
5. The cytoplasm of the early stages of the sac is closely 
packed about the egg. Later the egg becomes surrounded by 
an area much resembling a vacuole, which may affect the osmotic 
pressure and indicate a withdrawal of water, causing the oosphere 
to divide. 
6. The development of the embryo in parthenogenetic mate- 
tial is the same as found in normal material. — 
7, Parthenogenesis is becoming fixed in Thalictrum. 
a ILLiNors COLLEGE, 
Jacksonville, Ill. 
; EXPLANATION OF PLATES XII AND XI. 
16. 1 1. Section of young ovule showing archesporial cell (a). 
Fie. 2. The same, showing enlarging archesporial cell (2). 8 
Section of young ovule — integument — showing 
‘all 
ell (s). of the 
clinal division of tapetal cell (4); the nucleus 
2 upper and lower polar nuclei fusing a ns 
Young embryo-sac immediately after fusion pla , 
, area or vacuole about the — ‘syn, ee ; 
at, ee 
