272 Ward . — On Relations between Host and Parasite 
body in the cell-sap which inhibits or promotes the growth of 
the fungus ; and I did so by making a cold-water extract 
of the pounded fresh leaves 3 rapidly filtering through a stone 
or other filter, and sowing the spores in the liquid both raw 
and boiled. In all cases control sowings were made in water, 
and only those results regarded where the controls showed 
the spores to be vigorous. 
All attempts of this kind were in vain, however, since 
vigorous spores germinated equally well in extracts of the 
leaves of their own host-species and of their antagonistic host- 
species. See Table XL 
TABLE XL 
Expts. Nos. 739, 781, 782. Testing the germination of spores in extracts 
of the leaves of grasses. 
No. 
Date . 
Origin of spores. 
State of spores. 
Extract. 
Condition of 
extract . 
739° 
June 27 
B. mollis (1) 
Shed, from fresh 
leaves 1 day 
Young leaves 
B. mollis 
Masson filter 
not boiled 
„ b 
55 . 
» ( 2 ) 
55 
5 5 
Masson filter 
boiled 
» e 
55 
» (3) 
55 
Water only 
781 a 
Eh 25 
B. mollis (4) 
Kept 1 day in 
moist box 
55 
» & 
55 
(5) 
sj 
Filtered extract of 
B. sterilis leaves 
Un- boiled 
>> 0 
55 
(6) 
55 
55 
Water only 
Boiled 
782 a 
55 
B. secaiinus (7) 
55 
„ b 
55 
„ ( 8 ) 
55 
Extract of leaves 
of B. sterilis 
Un-boiled 
» c 
55 
„ (9) 
55 
55 
Boiled 
(1) One or two germinated. (2) More than 10 % germinated. 
(3, 4) Vigorous. (5, 6) Germinated freely. 
(7) Very vigorous. (8) Vigorous germination. 
(9) Equally vigorous. 
Of course these experiments , teach very little, since it can 
hardly be supposed that the cell-contents thus extracted are 
in the normal condition in which they would exist in the living 
cell. The positive results do show 5 however, that the failure 
of spores from B. mollis (see below for details) to develop 
pustules on B. S'terilis ) for instance, is not due to a mere 
exudation of some antagonistic soluble extract, — that the 
