Nov., 1922] KAUFFMAN AND KERBER HEART-ROT OF LOCUST 
cells either by way of the pits or directly through the cell wall. In the case 
of the parenchyma cells of the ray, the main threads of mycelium were 
found traversing the cells crosswise and sending branches into the cell. 
These hyphae were much more numerous in the medullary and wood 
parenchyma cells than in the tracheids, vessels, and fibers. 
Other sections were then made from portions about 7 cm. beyond the 
black zone, and stained with eosin. Here also hyphae. were present in 
relatively large numbers. The character of the mycelium could of course 
be compared with that in the sapwood immediately surrounding the sporo- 
phore of Trametes robiniophila. At first this comparison was disconcerting, 
since the hyphae ranged larger as one approached the fruiting body, varying 
from two to nine microns in diameter. Part of this, however, may have 
belonged to secondary fungi which had found a foothold in the old and 
crumbling sporophore or at its base on the dead wood. However, as one 
examined the more characteristic hyphae here, they were found to have a 
branching system in which end branches were abundant and became 
progressively more minute, thus corresponding to the size of the hyphae in 
the apparently sound wood. 
From what was found in these studies it became apparent that, although 
to all appearance the wood beyond the black zone was normal and exactly 
like good, sound locust wood, in reality there was no longer any sound normal 
wood present in this tree in a radial direction from the rotten core, and, 
from a cursory examination, this was also the case in a vertical direction 
from the uppermost rot to at least a distance of two feet. 
Supporting Evidence of Decay in the Apparently Sound Wood 
It seemed reasonable to infer from the presence of mycelium, hypha- 
holes, and some erosion, even if slight, that the apparently sound wood 
must already be weakened by this preliminary decay. It was therefore 
decided to make some tests of the compression strength of this wood so as 
to be able to make an approximate comparison with the strength of known 
sound locust wood as given in the tables by Newlin and Wilson (I.e.). It is 
to be understood in advance that the few tests made and the many vari- 
ables possible in dealing with decayed wood for such tests, can give us no 
more than a very general idea of the actual difference between such affected 
wood and sound wood. However, the results were sufficiently contrasting 
to demand attention. 
Two small blocks, about 6-cm. cubes, numbered ix and 2x, were cut 
out of the sound portion of section VI (fig. i), outside the black zone. Six 
blocks were cut from the upper portion of section IV (fig. i), situated 
vertically above the farthest point of the black zone, being in a portion 
where advance rot might be expected. The uppermost blocks were num- 
bered 4, 5, and 6. The ones from the next adjoining layer below were 
numbered i, 2, and 3. These blocks were situated from 20 to 30 centi- 
