[Vor. 4 
190 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
including the root system, and since it has been repeatedly 
stated in the literature that plants grown on land which had 
borne diseased plants were sure to contract the disease, an 
attempt was made to secure a root secretion possessing infec- 
tious properties. Roots were washed free from soil and then 
suspended in sterile distilled water. This method had to be 
abandoned, however, on account of bacterial growth. 
Since the disease is most pronounced in growing tissue, i. е., 
in young shoots, and since the infective principle may be iso- 
lated from the roots as well as from all parts of the plant, 
it must be granted that the infectious substance is transfer- 
able from one plant part to another. This implies that some 
of the infectious substance, originally in a highly diseased 
shoot or any which might be formed subsequently, might be 
transferred to other plant parts. The question then arose: 
If this assumption is correct, would it be possible to secure 
by ‘‘shoot secretion” or by ‘‘shoot exudation’’ a solution 
possessing infectious properties? Furthermore, would any 
oxidases be present in this secretion? 
An attempt was made to solve the question in the follow- 
ing manner: A large but badly diseased shoot of tobacco was 
removed from an old plant and after sterilizing the base with 
alcohol and rinsing with sterile distilled water, it was sup- 
ported, through a rubber stopper, in a wide-mouthed bottle 
containing sterile distilled water. A piece of glass tubing 
inserted into a small hole in the rubber stopper served as an 
inlet for sterile water stored in a separatory funnel. All 
joints were closed tightly with paraffin and wax. The bottle 
containing the base of the shoot was filled with water, leav- 
ing no air whatever in the chamber. As the water was re- 
moved by transpiration it was replenished from the separa- 
tory funnel serving as areservoir. This funnel was stoppered 
with a one-holed rubber stopper into which a piece of glass 
tubing stuffed with cotton was inserted. 
The system was allowed to run from April 1 to April 
19, 1916, at the end of which time the shoot had transpired 
485 се. of sterile water. Inoculations were made on April 19, 
1916, with the secretion, and checks were run with juice ex- 
