1898 | COMPARATIVE MORPHOLOGY OF PISTILS 307 
side of the pistil, instead of on the dorsal as in Myosurus. The 
ovule has but a single integument, and in the large size of its 
nucellus, as well as in its position in the pistil, much resembles 
that of Ranunculus (fig. 50). : 
FRAGARIA VIRGINIANA. The development of the pistil in this 
species is practically identical with that in the preceding. The 
only important difference is that the line in which the laminae 
meet is shorter, so that the style arises from well down on the 
front of the pistil. In this species is also found what probably 
indicates an advance in development beyond that shown in 
Potentilla, namely, quite often a pistil contains two ovules 
instead of one. This doubling is acomplished by the formation 
of one ovule on each of the thickened laminae, instead of on 
one only. Possibly this is the way in which the uniovulate 
genera, like Potentilla, have developed into the typical biovulate 
genera of the family (jigs.57-53). 
GENERAL DISCUSSION. 
A comparison of the structures exhibited by the pistil in 
these three families shows that each family includes genera with 
uniovulate as well as those with multiovulate pistils, and that 
the course of development of the uniovulate pistils is very 
similar in the three families, although in Potentilla and Fragaria 
it has been somewhat modified. 
It has been shown above that in Ranunculus the first sign of 
the ovule is the growth of a mass of cells in the axil of the 
developing carpel. The carpel elongates and becomes hollowed 
above by the upward growth of the laminae, which do not grow up 
Over the axillary mass of cells, but rather extend from it on each 
side to the apex of the carpel. By the elongation of the distal 
part of the axillary body the ovule is formed, and curves down 
mito the cavity of the pistil, while the proximal part remains in its 
original position, growing only in height and thickness. The 
laminae which extend from this body (called above the “axil- 
lary placenta’’) to the apex of the carpel, now approach each 
other at their edges, and meet in the median line, thus completely 
