300 BOTANICAL GAZETTE [ NOVEMBER 
made. The ovule bends down into the space between the lami- 
nae of the carpel. The single integument now begins to make 
its appearance, and the archesporium becomes visible as a spe- 
cialized cell. By this time the ovule has described an arc of 
120° from the position held by the axillary papilla when it first 
appeared. The development is now so rapid that by the time 
the archesporium has divided into two cells and each is begin- 
ning to divide again, the ovule has bent 30° more (fig. zo), and 
at the completion of the division has bent another 30°. At the 
- same time the apex of the carpel has passed through an arc of 
180°, and the main axis of the pistil has become parallel to that 
of the receptacle. A noteworthy fact in connection with the 
development of the archesporium is that the two megaspores 
nearest to the micropyle lie in a line nearly at right angles to the 
main axis of the nucellus (fig. zo). Soon after this stage is 
reached the pistil becomes closed through the meeting of the 
edges of the laminae. A front view of a nearly mature pistil 
shows that in this species, as in R. abortivus, the suture is haus 
like an inverted Y (fig. 79). 
Ranunculus ovalis, R., glaberrimus ? and R. delphinifolius show 
in their later stages the same structure as described above, indi- 
cating that they probably have a similar course of development. 
Myosurus minimus. This species has a long, narrow recepta- 
cle, in strong contrast to the short hemispherical one of Ranun- 
culus. On it is shown more vividly what is apparent to a slight 
degree on the receptacle of Ranunculus, viz., the acropetal 
development of the pistils. In Ranunculus the difference in 
age of the pistils on the different parts of the receptacle is only 
slight, and soon disappears. On the other hand, in Myosurus, 
even when the pistils on the lower part of the receptacle are well 
developed, others are just appearing at the top. As in the pre- 
ceding genus, the pistil appears as a slight papilla on the surface 
of the receptacle. As it elongates, its apex is directed slightly 
downwards. On the upper side of the pistil, next to the recep- 
tacle, is then developed an ney papilla whose axis, at first, 
forms an angle of about 35° with the surface of the receptacle, 
