No. 431.] STAGES IN PLANT GROWTH. 869 
Ranunculus acris L. (Buttercup). 
This species has the typical leaves three-divided, and the 
divisions considerably cleft and toothed, but the seedling starts 
off with fairly simple nepionic leaves (Pl. II, Fig. 4). Compar- 
ing the localized stages shown in the early spring growth with 
the direct development of the seedling, a great similarity is 
again noted. The plants were well started when observed, 
and weak growths had to be largely depended upon to show 
the stages. Pl. II, Fig. 5, shows a leaf of which one-half is 
comparable to the first nepionic leaf of the seedling. The 
other half is like the second nepionic. Here, then, is a leaf 
showing an acceleration of development in its two halves, — 
the half with two lobes being more accelerated than the other. 
This is often noted in compound leaves which are pinnate, — 
there being fewer leaflets on one side than on the other, — but 
is less often definitely shown in simple leaves. A first leaf of 
spring growth is figured, Pl. II, Fig. 6, which is comparable to 
the second nepionic leaf. The steps in complication of the 
lobes and nervation are shown in Figs. 7—9, and the seedling 
in its later development passes through similar stages. 
Beneath the flower the leaves become more simple usually 
by four distinctly reverse, but often varied, steps. The lower 
one of the four has about the same number of divisions as 
Fig. 8, but is drawn out into linear divisions. Higher up is a 
leaf that may be compared to the second nepionic of the seed- 
ling, or to the leaf figured in localized development (Fig. 5), in 
that it has five lobes. It is, like the preceding, deeply cut and 
elongated. Above this is a three-lobed leaf of the same char- 
acter and in its lobing comparable to the first nepionic leaf of 
the seedling. Just beneath the flower is usually a simple, elon- 
gated leaf, showing once more a localized stage in the adult 
plant more primitive than any of the stages shown in the 
direct development of the seedling. 
This species is one which is usually well developed in the 
early spring, and these earlier and weaker forms are hard to 
find without careful searching. The first formed leaves quickly 
dry, curl, and then drop off. 
