58 
BULLETIN 934, IT. S. DEPARTMENT OE AGRICULTURE, 
either of the groups of pots compared is seriously affected by parasites, the 
most convenient index of the comparative activity of the fungi used. In such 
a comparison as that between the Rheosporangium pots and the controls in 
experiment 68 (Table VII), accidental variations in emergence, of course, over- 
shadow the slight effect of the fungus, and the definitely determinable per- 
centage of loss after emergence is the only value which can serve as a basis for 
any definite conclusion. 
Table VII. — Results of inoculations on pine seedlings irith initial and reisolated 
strains of Rheosporangium aphanidennatus compared with parallel inocula- 
tions with Pythium < debaryaniuii. 
Reisolation source. 
Num- 
ber of 
pots. 
Num- 
ber of 
strains. 
Results. 
Experiment number, host, and 
inoculating fungus. 
Emerged 
(per 5-pot 
unit). 
Damp- 
ing-oft* 
(per 
cent). 
Survival 
(per 5-pot 
unit). 
No. 66, Pmus banksiana: 
Rheosporangium— 
Strain 229 
Edson from beet 
do 
5 
5 
10 
15 
15 
1 
1 
2 
3 
3 
63 
80 
78 
63 
72 
9 
52 
43 
43 
42 
58 
Strain 351 
39 
Strains 403 and 404 
Strains 405, 406, and 407 .. . 
Strains 417, 430, and 433 .. . 
Strain 229 from beet 
Strain 351 from beet 
Strain 351 from pine 
44 
36 
41 
50 
10 
70±2.7 
40 
42±3. 8 
25 
235 
...... 
75 
43 
15 
33 
64 
29 
Edson from beet 
do 
No. 67, Pinus banksiana: 
Rheosporangium — 
Strain229 
5 
5 
10 
15 
15 
1 
1 
2 
3 
3 
107 
88 
91 
92 
83 

6 
8 
4 
3 
107 
Strain 351 
83 
Strains 403 and 404 
Strains 405, 406, and 407 .. . 
Strains 417, 430, and 433 .. . 
Strain 229 from beet 
Strain 351 from beet 
Strain 351 from pine 
84 
88 
80 
50 
10 
90±2.4 
4 
86±2.9 
Controls 
23 
235 
47' 
87 
51 
5 
26 
83 
Pythium, average 
38 
Edson from beet 
do 
No. 68, Pinus resinosa: 
Rheosporangium— 
Strain 229 
5 
5 
10 
15 
15 
1 
1 
2 
3 
3 
105 
124 
102 
105 
100 


1 
5 
3 
105 
Strain 351 
124 
Strains 403 and 404 
Strains 405, 406, and 407 .. . 
Strains 417, 430, and 433 .. . 
Strain 229 from beet 
Strain 351 from beet 
Strain 351 from pine 
101 
100 
97 
50 
10 
105±2.3 
2 
102±2.5 
18 
235 
47" 
104 
86 

27 
104 
63 
A frequency graph based on the survivals of the 50 individual pots 
inoculated with Bheosporangium in experiment 68 yields a rather 
interesting asymmetrical curve (fig. 17). The shape of the curve 
is taken as indicating that in a large number of the pots the inocula- 
tion produced no effect, while in the smaller number of pots in which 
the inoculation apparently " took," the loss was rather heavy. This 
is a rather common phenomenon in inoculations which are only 
partly successful, part of the pots being free or practically free from 
loss, while others are nearly cleaned out. It will be seen again in 
