58 
Journal of Agricultural Research 
Vol. XXV, No. a 
Table V. —Dimensions of tubers of Green Mountains grown in IQ 2 I 
1921 
plot No. 
Strain. 
Description of lot 
measured. 
Number 
of tubers. 
Diseased 
with 
spindling 
tuber. 
Ratio of 
length/ 
width 
(L/W). 1 
Ratio of 
width/ 
depth 
(W/D). 1 
CT-28.... 
LK, secured in 
Spindling tubers selected 
100 
Per cent. 
98 
I. 722±.OI7 
I. I2I±.007 
CT-29.... 
1916 as mosaic- 
free. 
in winter of 1919-20. 
Spindling tubers selected 
in winter of 1920-21. 
Spindling tubers selected 
100 
99 
xoo 
x.863±.oi7 
i.6s8±.oii 
I. I22±. 008 
Y-6B.... 
LK, selected in 
149 
1.144±.007 
Y-6B. . . . 
1916 as mosaic. 
.do. 
in winter of 1921-22. 
Healthy tubers selected in 
winter of 1921-22. 
Grown on Caribou loam in 
101 
0 
1. 213 i. 012 
1.540±. 023 
1.3i8±. 008 
I. 242±.OII 
CT-13.... 
LK, selected in 
100 
40 
CT-13.... 
1916 as mosaic- 
free. 
.do. 
1921. 
Grown on Washburn loam 
xoo 
37 
0 
1.541 ±. 021 
1.302±. 013 
I. 222±. OIO 
MSS-S4.. 
B. 
in 1921. 
80 
1.327J:. 010 
1 Calculations were performed by the Biology Department, Maine Agricultural Experiment Station. 
Table VI. —Comparison of plots of Table V, giving difference between means and probable 
error of differencef also ratio between difference and its probable error 
length/width 
CT-28. 
Difference/P. E. 
CT-29. 
Difference/P. E. 
Y-6B. Spindling tuber. 
Difference/P. E. 
Y-6B. Healthy. 
Difference/P. E. 
CT-13. Caribou loam... 
Difference/P. E. 
CT-29. 
i4i±. 024 
(6:1) 
Y-6B. 
Spindling- 
tuber. 
.0641b. 020 
( 3 :i ) 
.205±. 020 
(10:1) 
Y-6B. 
Healthy. 
. 5091b. 021 
(24:1) 
• 6501b. 021 
(31:1) 
■ 445 ±-°i 6 
(28:1) 
MSS-S4. 
.420±. 021 
(21:1) 
• 56idb. 021 
(27:1) 
• 356 ±.oi 7 
(21:1) 
.089±. Ol8 
(S :l ) 
CT-13. 
Washburn 
loam. 
.001 ±. 031 
(1:31) 
WIDTH/DEPTH 
CT-28. 
Difference/P. E_ 
CT-29. 
Difference/P. E- 
Y-6B. Spindling tuber 
Difference/P. E- 
Y-6B. Healthy. 
Difference/P. E_ 
CT-13. Caribou loam.. 
Difference/P. E_ 
001dt. oil 
(1:11) 
.023 ±. OIO 
(2:1) 
.022 zb • Oil 
(2:1) 
.197 zb. on 
(iS:i) 
,1961b. on 
(x8:i) 
-I 74 ±- on 
(16:1) 
.206±. 012 
( r 7 :i ) 
.205 ±.013 
(16:1) 
.183 zb. 012 
(15:1) 
.oo9±. 013 
(1:1.5) 
O20zb. 015 
(1-3:1) 
1 Calculated as the square root of the sums of the squares of the probable errors of the means. 
Further infection experiments including inoculation with leaf mutila¬ 
tion, tuber and stem grafts, and aphids, were initiated on plants in the 
greenhouse and in cages in the field, as well as under open field conditions. 
The procedure in these infection tests was similar to those observed 
with such operations in connection with the writers' studies on mosaic 
and leaf roll of potato. The results of these experiments are presented 
in Table VII. 
