1911] COOPER—LAYVERING AMONG CONIFERS 373 
Cases were found in which the layered branches themselves had 
given rise to secondary groups, the connection with the original 
tree being still maintained. 
There is abundant evidence that in many cases the layered 
branches become independent trees by the decay of the connecting 
Portions. In fig. x it may be seen that the layered branch near its 
Point of origin is extremely slender, while in the region where the 
roots have developed and in the subaerial portion it is thick. The 
_ transition from thin to thick is frequently very abrupt. This 
Points toward the conclusion that the young tree is deriving by 
far the greater amount of its sustenance from its own root system, 
and that if the connection should be broken it would be entirely 
able to care for itself. The underground portion was often so weak 
that in spite of the greatest care it was severed in the process of 
uprooting. In many cases also the decumbent bases of independent 
young balsams indicate that they once had a horizontal connection 
With some neighboring tree (see a in fig. 1). 
Some examples will make clear the various forms which the 
habit of layering takes. 
1. A very typical case is seen in fig. 1. The oldest stem shown 
in the photograph is at r (all but the base has been removed for the 
Sake of clearness). That this is itself a layered branch of a still 
older tree is indicated by the long rhizome-like structure (a) extend- 
ing horizontally toward the left. The character of the well formed 
young tree 2 as a layered branch of 7 is evident. Branch 2 is one 
meter high. Branch 3 is connected with 2 by way of c, and has 
itself given rise to 4; the latter finally has produced 5. There are 
thus represented five generations of upright stems produced by 
Ttepeated branching and layering. Each except the youngest pos- 
Sesses a well developed root system of its own, and in every case 
except the last the horizontal connecting stem behind the region 
of vigorous rooting has remained practically without further 
development. The constriction where b joins 1 is especially evi- 
dent. Branch 5 receives all its nourishment from 4, and the latter 
Probably still derives much from 3. 
2. A balsam 2 meters high, which had died very recently at the 
age of 46 years, itself apparently a layered branch, had given rise 
