190 
The N.Z. Journal of Science and Technology. 
[Nov. 
Table No. 2.—Summary of Tests of Insulators taken from Transmission-lines. 
At 100,000 
Volts. 
At 50,000 Volts. 
Poles. 
Line. 
Number 
of 
Insulators. 
Number 
failed, 
Head to 
Pin. 
Number 
failed 
on Three 
Shells. 
Number 
failed 
on Two 
Shells. 
Number 
failed 
on One 
Shell. 
Number 
O.K., 
all Shells. 
Taken off at Random. 
856-59 
N. 
12 
1 
1 
0 
2 
8 
722-29 
S. 
24 
1 
3 
8 
6 
6 
600-03 
s. 
12 
0 
0 
2 
3 
7 
494-97 
N. 
12 
0 
0 
0 
10 
2 
44, &c. 
N. 
6 
3 
1 
1 
1 
0 
66 
5 
5 
11 
22 
23 
Taken off 
on Suspicion due to 
Special Glowing or Crackling. 
475-583 .. 
S. 
3 
1 
0 
0 
1 
1 
238-404 .. 
s. 
7 
2 
0 
3 
1 
1 
58-421 
N. 
9 
1 
0 
4 
4 
0 
19 
4 
0 
7 
6 
2 
YELLOW-LEAF DISEASE IN PHORMIUM TENAX.* 
By L. Cockayne, Ph.D., F.R.S. 
. 1. General. 
This report is concerned chiefly with the behaviour of a number of carefully 
chosen plants, growing naturally under more or less different conditions, 
especially of moisture in the soil, in the flax areas of Miianui and Ashlea. 
Plants of every degree of health were selected, from such as were extremely 
healthy and vigorous to those which were stunted and almost dying. The 
plants were labelled during the concluding days of February and the 
beginning of March (21st February to 6th March), 1918, and notes were 
taken as to their condition. Subsequently the marked plants were examined 
at intervals of not less than three months, so that changes in their con¬ 
dition could be ascertained. 
In addition to examining the marked plants, some attention was paid 
to the general condition of the flax areas, while certain of these not examined 
by me previously were visited. Thanks also to an important investigation 
I am carrying out for the Department of Agriculture, I have travelled 
extensively through the South Island and had an opportunity of seeing 
Phormium tenax growing in many localities and under diverse surroundings. 
It must not be forgotten that this report, so far as it concerns the 
marked plants, deals only with experiences of fourteen months, a time 
altogether too brief to enable any definite statements to be made. The 
conclusions at the end of this report cannot, therefore, be looked upon 
as final. Nor have I been concerned with the disease as a disease ; my 
investigations have been directed rather towards attempting to ascertain 
the conditions of soil and climate favouring or restraining yellow-leaf, and 
* The final report on an investigation carried on on behalf of the New Zealand 
Flax-millers’ Association, dated the 2nd July, 1919, and revised by the author, 
11th November, 1920. 
