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Tur DISSEMINATION OF DisEASE BY MEANS OF THE SEED OF 
THE Host Puant. 
By M. F. Barrus. 
(Abstract from thesis presented in June, 1908, at Wabash Collegee, Craw- 
fordsville, Indiana, for Eastman Biological Prize.) 
It has been known for a long time that diseases can be spread by 
means of the seed of the host plant. As early as 1730 Jethro Tull recom- 
mended a change of seed to avoid smut. Since then the list of such dis- 
eases has steadily increased until now there is a large number of them. 
A knowledge of the method by which infection of the seed takes place 
and of the subsequent growth of the parasite is of value, since it will re- 
veal a vulnerable point of attack, if there be any, in seeking means of 
controlling the disease. It is the purpose of this paper to indicate briefly 
those diseases of cultivated plants which are disseminated by means of 
the seed of the host plant and to point out the method by which the seed 
becomes infected. 
These diseases can be divided into two classes, those which infest the 
seed internally, i. e., the organism entering the maturing seed and existing 
within in a dormant condition until the germination of the seed; and those 
which infest the seed externally, i. e. the organism or its spores becoming 
attached to the surface of the seed and entering the host plant at the time 
it germinates. The diseases belonging to the former class are the An- 
thracnose of Beans, the Blight of Peas, the Loose Smut of Wheat and 
Barley, and possibly a few of the Rusts. Under the latter class may be 
included most of the Smuts, the Wilt of Flax, and probably some of the 
Rusts and a few Bacterial diseases. 
BEAN ANTHRACNOSE. 
Colletotrichum lindemuthianum (Br. & Cay.) on Phaseolus vulgaris. 
The fungus causing this disease survives the winter in the seed of 
the host plant. If the affected pods are allowed to ripen on the vines, the 
mycelium of the fungus penetrates further and further, eventually entering 
the seeds, usually causing them te become spotted (Figs. 1 and 2). Here 
