4 
Karsten,* FrankJ and Hofmeister§ have shown that the cell-walls 
within which gum is deposited disintegrate during the process of 
secretion, thus furnishing material for the latter. But both Hof- 
meister and Frank think that the gum begins to be formed in the 
cells before their disintegration commences, otherwise the large 
amount of the product could not be explained. Frank|l gives a 
figure of a transverse section through a branch of a cherry-tree 
affected with gummosis, which in several respects very much re- 
sembles Fig. 6 of our plate. The same author has another figurelF 
of a whole branch, a considerable portion of w4iich has been changed 
into the gummous substance, and which could very well be compared 
to Fig. 1 of the plates in the Smithsonian Report representing a root 
encircled with a mass of tuckahoe. 
Gummosis (and, to a certain extent, resinosis) is thought to be 
a process of degeneration accompanying the gradual cessation of the 
vital functions of some portion of a plant. An accumulation of 
plastic material takes place in the affected parts, and these are 
gradually absorbed and finally entirely destroyed. The causes of 
this process are chiefly mechanical injuries, e.g.y the breaking off of 
branches, the tearing off or bruising of the bark, etc.; but various 
other causes that tend to diminish or destroy the vital energy of 
some organ or of the entire plant may produce the same effect.^ 
I have somew^iat digressed from my subject, because it is my 
opinion that a close comparison of the nature and origin of the gums 
with those of tuckahoe will reveal many analogies which might en- 
title us to call the pathological process of which tuckahoe most likely 
is the result, pectosis. In that case the views of Rev. M. J. Berkeley 
and other mycologists (see Bulletin,/. ^.) would no longer be mere 
conjectures. It is not even necessary to assume with Currey -^nu 
Keller (/.^.) that the fungus found in tuckahoe is the cause of its for- 
mation. As this fungus has not yet been proved to be parasitic on or 
in the living root-cells, while we have seen that it grows on the pec^m 
granules, we might, with good reason, consider it a saprophyte ^y^^ 
hosts of its kind that thrive on disorganizing vegetable or animal 
substances. However, it remains very much to be desired that some 
competent mycologist should take this fungus in hand and throw fuH 
light upon its life-history, thereby at the same time solving the 
*' puzzle" called tuckahoe. 
Explanation of Plate xlul— Fig. i. Transverse section from the surface or 
'* bark " of tuckahoe, magnified x 140. The large cells and cell-fragments belong 
to the projecting shreds of woody fibres, the small circles and corresponding P^'^J 
allel lines represent the hyphce (transversely and longitudinally); the larger roundea 
bodies are pectin granules. Fig: 2. Radial section from the same part as ^^S* /' 
X 140. 
striation 
The cells show the characteristic bordered pits of coniferous wood, also t 
of the disintegrating walls; the edges are not so sharply defined as repre- 
* Bot, Zeitttng^ i857» p. 319. 
% Pringsheim's y^/zr^.. Vol. v.. p. 25. 
^ rflanzenzelle, p. 234. 
I Die Krankheiten der Pflanzen, p. 85. 
T[ Ihid^, p. 90. 
