Contributions to the embryology of the Ranunculaceex. 
WITH PLATES XVII-—XxX. 
DAVID M. MOTTIER. 
(Concluded from page 248.) 
Of the three species of Ranunculus examined, R. abortivus 
is most abundant in this vicinity thriving well in the dry soil 
of open woods and meadows, while the other two, R. vecurva- 
tus and R. septentrionalis, seem to prefer the moist soil of 
more dense and shady woods and along water courses. We 
shall direct our attention first to 
Ranunculus abortivus.—The carpophyll may be said to con- 
sist of a short stalk or petiole and a broader portion, the lam- 
ina. The ovule arises as a small protuberance at the junction 
of petiole and lamina, but, of course, before any differentiation 
into these two parts is perceptible. The lamina soon broad- 
ens, the edges bending upward to form acrescent shaped cup 
or cavity into whose opening the rudimentary ovule projects. 
A longitudinal radial section of a carpel thus far developed, 
presents a picture closely resembling a partly closed hand 
with the thumb pointing downward toward the palm, the 
thumb representing the rudiment of the ovule (fig. 412). At 
this stage of development the edges of the lamina have not 
quite organically united, a fact made clear by fig. 410 
which is a transverse section cut in the plane r—-x of fig. 414. 
The initial cell of the embryo-sac is hypodermal. The sut- 
rounding hypodermal cells by their behavior seem to be sug- 
gestive of a sort of archesporium (figs. 31, 32). 
Before the first division it elongates a good deal, and some- 
times becomes very broad (fig. 33). In the majority of cases 
observed only the lower of the two cells resulting from the 
first division divided again (fig. 38). Sometimes, however, 
both cells divide as in the preceding genera (fig. 39) though 
this is less frequent in the genus Ranunculus. n a number 
of instances the nucleus in the upper cell divided without be- 
ing followed by the formation of a cell wall (fig. 35), and 1m 
others a longitudinal division of this cell took place. From 
fig. 34 it seems probable that two cells have begun to develop 
into embryo-sacs. Here only two cells were formed from 
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