No. 431.] STAGES IN PLANT GROWTH. 871 
toothed. Ten seedlings in a single pot were compared as to 
their first nepionic leaves as follows: 
Both first leaves simple . : 
One simple, one one- hod ‘ 
One simple, one two-notched 
Both one-notche 
One one-notched, one Showin 
Both two-notched . Sr 
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This crude table is enough to show the individual variation 
of seedlings under the laws of acceleration of development 
and the consequent necessity of making sure of the typical 
stages. 
The second pair of nepionic leaves have typically two lateral 
teeth on each side in some cases, with more complicated forms 
than this, but even in this case, so far as seen, only one of the 
pair has the more complicated form, the other being typical. 
The midrib begins to be distinct. 
The next leaves are quite dissected and begin to decidedly 
resemble the typical adult leaf. It may have in the third pair 
of nepionic leaves from three to seven or more lateral teeth on 
each side, and these may also be divided or notched. 
Among the adult plants at the very base in the first spring 
growth, leaves may be found which repeat many of the simpler 
conditions. Fig. 6 is decidedly three-parted, much as the first 
nepionic leaf in many ways, but less strikingly so than Fig. 7, 
which is quite like the second nepionic leaf of the seedling. 
Figs. 8 and gare like later seedling stages. All of these leaves 
are from the base of fresh spring growths. 
The flowers of this plant are in a dense corymb, each portion 
of which comes from the axil of a leaf. The leaves in the 
upper part become inconspicuous, but repeat, however, many of 
the characters seen in the seedling and in the reverse order, 
those immediately below the upper heads being like the first 
and second nepionic leaves in the number of teeth and general 
character. This is exactly comparable to the principles of 
senescence of the late Professor Hyatt, stages occurring in the 
old age of the individual corresponding to stages passed through 
