The development of the embryo-sac of Arisaema triphyllum 
F. L. Picketr 
(WITH PLATES 13 AND 14) 
The development of the embryo-sac of Arisaema triphyllum 
was first studied by Strasburger (1) in 1879, and later by Mottier 
(2), who published his observations in 1892. Campbell (3, 4) in 
his studies on the Araceae has referred to the findings of Mottier 
and used them as a basis for comparison. Gow (5), in his intro- 
duction to the study of the embryogeny of Arisaema triphyllum, 
reviewed the development of the embryo-sac, confirmed the 
findings of the second study mentioned above, and added observa- 
tions of the division of a primary archesporial cell to form embryo- 
sac initials. The writer has been able, after the examination of 
several hundred ovules, to verify most of the stages in the embryo- 
sac development as set forth in the above-mentioned articles; 
but has found some notable points of difference touching the 
formation of megaspores from the primary archesporial cell. On 
the other hand the writer has found that in some respects the 
development of Arisaema triphyllum agrees very closely with that 
of Symplocarpus foetidus as shown by Rosendahl (6) in 1909. 
The material for the present study was collected in proper 
season through four years, 1909-12. The various stages were 
secured from as many habitat conditions as possible. All fixing 
was done in the field or immediately after the return to the 
laboratory. Parts of young spikes and separate pistillate flowers 
of older spikes were fixed, some in strong chrome-acetic acid 
mixture, and others in chrome-osmic-acetic acid mixture, for 
24-30 hours, then washed in running water for 24 hours, and finally 
gradually dehydrated. The blackening from osmic acid was in 
some cases removed by treatment of the whole specimens with 
hydrogen peroxide; but this resulted in considerable shrinkage, so 
that the specimens were of very little value. The sections were 
stained with safranin-gentian violet-orange G, with occasional 
special staining of cell walls with Bismarck brown. 
