a 
APRIL 11, 1884.] 
of trees grow from artificial planting much more 
readily and rapidly than others, the cotton- 
wood exceeding all others in these respects. 
Next, perhaps, comes the common locust, 
which, however, was not indigenous within 
the prairie region; but the cultivation of this 
valuable tree, which was formerly practised 
there with great success, was suspended, some 
twenty years ago, in consequence of the rav- 
ages of the ‘ borer.’ Then follow certain trees 
which I name in the order of the apparent 
readiness and rapidity of their growth ; namely, 
white maple, elm, black walnut, linden, oaks, 
and hickories. : 
The greater readiness and rapidity with 
which some of the trees named will grow by 
artificial planting do not imply that they have 
any greater vitality or permanence after their 
growth is established than the others: it only 
implies that they have greater promptness of 
vitality in establishing their growth. For ex- 
ample: the cottonwood may be grown with 
almost equal facility from the seed or from 
cuttings ; but the oaks, hickories, and walnuts 
can be successfully grown in practical forestry 
only from the seed. Even the transplanting 
of these trees is not usually successful, but 
their cultivation from the seed is easy and 
natural. 
While these facts concern the practical cul- 
tivator especially, they also have an important 
bearing upon the question of the original dis- 
tribution of forests. The experiments re- 
ferred to also show that not only will certain 
of the indigenous trees of the prairie region, 
which preferably grew upon the moist soil of 
the river-valleys, grow thriftily upon the up- 
land prairie-soil, but that all kinds of the indi- 
genous trees, as well as many others, will also 
grow thriftily upon all varieties of that soil. 
It is true that some of the soils — those of the 
loess of the Mississippi valley, for example — 
were more ready than others to receive tree- 
growth by the natural process of distribution ; 
but this does not alter the fact, that all varie- 
ties of prairie-soil will receive and support an 
abundant forest-growth, when easily available 
artificial conditions are applied, and controlla- 
ble unfavorable conditions are removed. 
I have so far spoken of the facility with 
which trees will grow upon prairie-soil by arti- 
ficial planting. Ihave now to speak of another 
phase of the subject of the propagation of 
forest-trees; namely, that of their natural 
encroachment upon prairie surfaces. 
The borders of the primitive prairies, where 
woodland and prairie joined, were usually oc- 
cupied by thickets of hazel and other shrubs, 
SCIENCE. 
44] 
mingled with stunted trees. Also, for consid- 
erable distances out upon the grassy surface, 
there were numerous dwarfed stubs of oaks, 
hickories, and other trees, sometimes putting 
out small branches, only to be destroyed in a 
year or two by the fires; sometimes burnt to 
the ground, but their roots remaining alive, 
and sending up vigorous shoots next year, only 
to be burnt off by the next fire which should 
sweep across the adjacent prairie. The prairie 
borders were thus kept stationary year after 
year by the fires. It was a perpetual contest 
between vigorous and progressive vegetable 
life and its deadly enemy, with material con- 
quests upon neither side. 
As soon as the annual fires were stopped by 
the increasing inhabitants, which they did as ~ 
a necessary provision for safety, the natural 
encroachment of the forests upon the prairie 
borders went on so vigorously, that it required 
the preventive means of agricultural occupancy 
to check it. 
There are now many thousands of acres of 
land in the great prairie region, which are 
densely covered with a full variety of mature 
forest-trees, which were parts of grass-covered 
prairie borders when the country was first set- 
tled. In many cases, cultivated farms, which 
were originally established upon the open prai- 
rie borders, are now surrounded by woodland, 
which has become such by natural means since 
the fires were prevented. Doubtless, local con- 
ditions have varied the rate of encroachment of 
forest-trees upon the prairie borders ; but it is 
plain that the natural tendency is, and always 
has been, in that direction. ‘This tendency is, 
in fact, the leading element in original forest 
distribution, — a process, which, in the present 
case, beginning with the close of the second 
glacial epoch, probably progressed mainly from 
the eastward and south-eastward. This process 
of distribution was only partially accomplished 
in the prairie region when it was first known 
to white men. No doubt, the uncompleted 
state of the distribution was primarily due to 
the want of necessary time for its accomplish- 
ment since the distribution began; but it was 
certainly long held in check by the annual 
prairie fires. 
It is not my present purpose to discuss geo- 
logical questions with regard to the prairies ;: 
but since the remains of trees, which have not 
unfrequently been exhumed from beneath the 
surface in that region, have been supposed to 
afford proof of the former forested condition of 
the prairies, it is desirable to refer briefly to 
that subject. It is no doubt true, that the great 
prairie region was formerly occupied by a forest- 
