40 
EIGHTH REPORT. 
A STIMULUS TO THE PRODUCTION OF CELLULOSE AND 
STARCH. 
J. B. DANDENO. 
To organize starch or cellulose, in the laboratory, by chemical pro¬ 
cesses merely, has never, so far, been accomplished. Plants develop 
cellulose in the ordinary processes of growth, and they produce starch 
in the chloroplast under proper conditions of light and temperature, 
if the necessary substance be present; but the action of the protoplast 
seems to be necessary for the development of either starch or cellulose. 
Such action is very likely a chemical one, but the chemist has never 
been able to imitate the process, much less to duplicate it. Anything, 
therefore, which tends to throw light upon the question is eagerly 
sought by both the chemist and the physiologist, to say nothing of the 
bacteriologist. 
The whole problem of the development, the interactions and the func¬ 
tions of cellulose in plants is probably one of the most interesting in 
the whole field of physiology, but it is only one phase of the problem 
that will be examined here. Shqeropsis malorum . Pk. (black rot of ap¬ 
ple) seems to produce cellulose in the cell-walls of the apple in the 
course of decomposition of the fruit. It also produces starch in the 
cells invaded by the mycelium of the fungus. 
Fungi build up cellulose, closely resembling the cellulose of higher 
plants, in the walls of their cells. Such cellulose, however, de Bary 
called Fungus-cellulose because, in some cases, a modification of the 
ordinary cellulose test reagents had to be employed in order to bring 
out the typical cellulose reaction. The process of transformation of 
cell wall substance and cell content of the host plant, into the body of 
the parasite, is a process common enough in the vital activities of all 
plant parasites, and it is indeed a necessary operation in the life 
of the parasite. But that the fungus parasite can stimulate the host 
plant to build up starch, or thicken its cell walls, is a different matter. 
This occurs not infrequently among certain groups of parasites, e. g., 
Puccinia graminis. This fungus stimulates the host plant to produce 
more cells in the neighborhood of the mycelium than in a like portion 
of the barberry leaf which is not affected. It stimulates, therefore, 
the production of cells, and, at the same time, in these cells, starch 
grains are formed. These starch grains are what might be called stored 
starch. Though they are in the portion of the host in which starch is 
organized. But in each case the host is a living plant, and, as such, it 
is capable of modifying its tissue as the result of response to stimuli. 
With the black rot of apple, the case is somewhat different, because the 
apple itself (the fruit) has long been severed from the tree and is no 
longer considered a growing, or, even, a living organ. It has also been 
