492 
J. G. GROSSENBACHER 
removed. Fig. 44 shows the same tree as that in Fig. 43 with the 
loose bark removed, making it apparent that the tree was half girdled, 
though only a fairly narrow band (not exceeding 17 cm. in vertical 
width) was involved. The loosened bark shown as removed in Fig. 
45 had several short radial clefts, though otherwise the bark appeared 
normal while it was still on the tree. When removed, the inner 
surface of the bark and the wood thus exposed had a rusty brownish 
color. On cutting with a knife it was found to contain numerous 
closely scattered, small dead spots, which in some places had coalesced 
to form ragged, dead patches as much as one or "two centimeters in 
diameter. These patches often involved all but the outermost layers 
of the cortex and sometimes showed through the periderm or scaly 
outer bark in the form of dead spots from one to five millimeters in 
diameter. In places, however, this loose bark was found to have 
developed a new cambium in addition to bladdery outgrowths from 
the inner phloem, thus tending to re-establish connection with the 
wood cylinder. Similar, though scattered, outgrowths had also de- 
veloped from outside the wood cylinder, but the actual connection 
established was evidently slight; for on June 2^, when it was removed, 
considerable areas of these proliferations had died and turned a rusty 
brown. In fact, disorganization seemed to have set in over a large 
part of the inner surface of this bark. 
When, on May 7, the loosened bark was removed from the tree 
shown in Figs. 43 and 44, only a slight discoloration was noticed on 
the contact surfaces. The loosened bark appeared perfectly normal 
on the outside, with the exception of the presence of a wide radial 
cleft. , Numerous scattered groups of dead tissue were found in the 
older phloem and inner cortex. Proliferation growth had been abun- 
dant, and in a few places it appeared that cambium was in process 
of formation. 
In cases of injury in which the affected bark does not die and where 
but one substitute cambium develops, only the discolored line in the 
wood afterward remains as a permanent record. This line is marked 
oc in Figs. 18 and 19, Plate XXIII, and 37, Plate XXV. Fig. 49, 
Plate XXVII, is an especially clear illustration. It represents a 
cross-section of the base of a large apple-tree trunk from an orchard 
in which the initial injuries, leading to the development of crown-rot, 
had occurred on many trees the same number of years back, as is 
indicated by the radial-growth zones outside the conspicuous line of 
