34 The N.Z. Journal of Science and Technology. [Mar. 
in the science of liquefaction, and by diagrams. Following upon the 
explanations, the lecturer carried out some very remarkable and spectacular 
experiments showing the results of extremely low temperatures. These 
included the liquefaction on the stage of atmospheric air and pure oxygen. 
Discussion on the Flax Industry. 
The problems of the New Zealand flax industry were discussed at a 
general session of the Congress on the morning of Thursday, 27th January. 
The subject was introduced by Mr. A. Seifert, who gave an account 
of the dimensions of the industry, and mentioned the ravages of the • 
yellow-leaf disease, which had caused during the last year the abandon¬ 
ment of 5,000 acres of flax swamp. He compared the return per acre of 
land under flax with that of land grazed for dairy-produce, and concluded 
that the growing of flax was a much more profitable method of utilizing 
the land. Compared with the difficulties confronting other types of fibre, 
New Zealand flax was in a favourable position, but it was necessary to 
obtain immunity from the yellow-leaf disease. His firm had made some 
experiments with fertilizers, and, though it was too early to give definite 
results, they were so far in favour of the use of fertilizers, especially super¬ 
phosphate. 
Dr. J. W. Mcllraith spoke on the economics of the flax industry. The 
price of flax had steadily risen, and at a greater rate (136 per cent, in the 
last twenty years) than other agricultural products (104 per cent, during 
the same time). In the “ nineties ” flax formed only \ per cent, of our 
exports ; now it formed 3 per cent. He concluded that it would have been 
profitable to grow more flax in the past, and mentioned the existence of 
large swamp areas which he thought should be utilized. 
Mr. A. H. Cockayne mentioned the improvement of the Manawatu swamps 
by draining, after which pure stands of flax automatically sprang up. The 
district now possessed 23,000 out of the 50,000 acres of flax in New 
Zealand. The gross returns per acre were greater than for any other form 
of agriculture except orcharding. Diseases were now the limiting factors 
of production ; of these the yellow-leaf disease was the most serious, 
rendering 6,000 acres unproductive. He exhibited specimens of diseased 
plants, showing how the outer leaves of the fans assume a yellow colour and 
ultimately shrivel up, while the next inner leaves are attacked, and so on. 
The problem his department had to solve was whether the disease was 
caused by bacteria, fungi, insects, or other pests. They had isolated six 
species of bacteria infecting the roots, none of which had developed under 
experimental conditions any pathogenic symptoms. A nemotode worm 
had also been investigated—one of these worms is the cause of a disease 
called “ yellow stripe ” in the similar monocotyledonous daffodils—but the 
numbers found were not sufficient to account for yellow-leaf disease. 
Insects also failed to account for the disease, though they caused trouble 
of another sort. Finally a fungus had been isolated, Ramularia ■ phormii , 
and was held to be the cause of the disease. The delay in its isolation 
was the difficulty of sterilizing the surface of the roots, owing to their great 
porosity. Field experiments showed that only that portion of the root 
which absorbs water could be infected ; this was not the primary root, 
but the secondary or tertiary branches. Once these are infected, the 
fungus spreads and reaches the primary roots. As it destroys the water¬ 
absorbing roots, the fungus prevents the absorption of water. When 
the swamps get very dry the disease spreads very rapidly. Unless the 
disease can be eliminated the industry is doomed. The fungus had been 
