To BIRD’S-EYE FORMATION IN THE Woop OF TREES. 33 
I have found that the branches which bear those structures 
invariably die prematurely. The appearance presented by such 
a branch is illustrated in Plate XI., Fig. 50, where opposite sides 
of an abnormal branch are shown. : 
So far I have found on the dead branches, without exception, 
the fructification of one and the same fungus, but as yet I do not 
know whether the fungus may have anything to do with the for- 
mation of the aerial roots or not. 
In Fig. 50 the part of the stem which produced the roots is 
dead, but just below the place where the roots ceased to come 
off were two branches which were still living. 
General Remarks. — 
In discussing the occurrence of abnormally broad medullary 
rays, Kuster! gives, in a foot-note, a reference to an article by 
Sorauer’, of which I append an extract. 
“The canker-like ‘Rindhypertrophe’ of the rose, which, 
according to Sorauer, is probably due to over-feeding, is accom- 
panied by certain abnormalities in the structure of the wood. 
Those abnormalities consist in the formation of four abnormally 
broad medullary rays, which run from the pith to the periphery 
of the wood, dividing it into regular compartments. The tissue 
of the bands is composed of very porous wood-parenchyma. On 
two opposite arms of those abnormally broad medullary rays 
adventitious bud-rudiments were formed in the cambium-zone, 
which had produced a thick wood-cylinder pointing in an outward 
direction, but had not pierced the outer tissues. In the neigh- 
bourhood of these internal bud-cones all the elements were 
increased.” 
Further, Frank? mentions the fact that adventitious buds. 
arise on the roots of Pyrus japonica,Rubus, Prunus, and others 
from primary medullary rays. 
It would therefore appear that medullary rays are capable of 
giving rise to adventitious shoots in some cases, in others to 
adventitious roots. It would be interesting to know the condi- 
tions which determine whether the adventitious organ is to be 
1Kuster, Pathologische Pflanzen Anatomie (1903), p. 
* Sorauer, Zeitschrift fur Pflanzenkrankheiten, Vol. vi (1898); P . 220. 
*Frank, Lehrbuch der Botanik, Vol. I1 (1893), p. 5 
