Vol. XVII. No. 421. 



THE AGRICULTURAL NEWSs 



17& 



is discovered or bred which is naturally self-feniiized. 

 The effect of such mixture is enormously increased 

 year by year. The presence of 2 per cent, of natural 

 hj'brids in a handful of seed of pure strain can convert 

 80 per cent, of the individuals of that strain into 

 rogues at the end of only three years. 



Trials were made of the four selected strains: one of 

 them turned out to be definitely superior to any other 

 Egyptian cotton from the agricultural point of view: a 

 second was remarkably good in every spinning test: a 

 third, first selected for propagation as being thoroughly 

 well known, turned out only moderately successful: while 

 the fourth, selected for the length of its lint, although 

 its yield was no better than had been anticipated, 

 showed that Kgypt could grow cotton comparable to 

 that of the Sea Islands, if the necessary trouble were 

 taken. 



The cultivation of these four strains has now been 

 abandoned, but the importance of guarding against 

 natural crossing has been shown by the fact that, one 

 .strain which had been isolated sin^e 1906, and was 

 pure when sown in the field eight years later in 1!U4, 

 was badly contaminated by 1!I17. 



From the above it will be seen that the ordinary 

 commercial crop of cotton in Egypt, is, from the genetic 

 standpoint, far from being derived from pure strains; 

 there are innumerable differences existing in the plants 

 of a single field. Amongst these are those relating to 

 the length of the lint, over and above such modifica- 

 tions of lint length as may be caused by environment. 

 These genetic differences take two forms: (1) differences 

 in the mean maximum length of the lint produced on 

 any one seed, and (2) differences in the degree of 

 variation in lint length in different parts of the same 

 seed. Consequently a single plant (or equally, a pure 

 strain population of plants") may produce most irregular 

 lint, the hairs from one end of each seed being very 

 uuich shorter than those from the other end; while 

 every gradation is found between these extremes. On 

 the other hand, suitably chosen pure strains are capable 

 of producing lint more regular in staple than are our 

 present cottons. 



The method of obtaining the length of cotton 

 lint from the mean maximum width of the halo made 

 by combing out the fibres gives' a remarkably accurate 

 result in measuring lint attached to the seed. The 

 limitation to the method is its inapplicability to 

 ginned lint. A method is now available for dealing 

 with the accurate measurement of ginned lint bv 



a mechanical arrangement, invented by Dr Balls, which 

 is descrioed at some length on another page of 

 this issue. It seems that this machine woidd 

 offer possibilities of useful application in all places 

 where experimental cotton growing is carried out. It 

 is possible by the use of it to take a sample of 

 raw cotton, treat it for a few minutes only in aa 

 automatic machine, weigh the graduated produce of 

 the machine's activity, and at the end of half an hour 

 to be able to plot frequency curves of a rea.sonable 

 and measurable degree of precision, showing the \ ari- 

 ation of length of staple within the sample. 



At the conclusion of his paper Dr. Balls pointed out 

 that enquiries, begun with a scientific object, simply to 

 strengthen tlie foundations of knowledge about the 

 cotton plant, have quite unexpectedly produced results 

 of economic significance. In research of this kind 

 there can be no distinction between pure and applied 

 science. It is really quite immaterial what such 

 research is called, for it is in intention and execution 

 strictly scientific work carried out on an economic 

 material. 



ECONOMIC VALUE OF GRASS TREES. 



The ecoDomic value of grass trees {Xantlwrrhea spp.) has 

 formed a subject of investigation in Soutfi Australia. Atten- 

 tion was drawn to the malter, say.s the Sydney ^furi/in.}^ 

 ZTfya/;/ (quoted by the ToKnial of tlu Koyal Society of Arts), 

 on account of the fact that the resin known as yacka gum 

 appears likely to be of considerable commercial importance 

 in the future. Grass trees are not found out>-.ide 

 Australia, and they yield products the like of which 

 are not obtained from other plants. The grass tree, it may 

 be mentioned, is a plant with shrubby stems, tufts of long 

 wiry foliage at the summit, and a tall flower stalk, with 

 a dense cylindrical spike of small flowers. 



The only product at present of commercial impor- 

 tance obtained from these trees, is the resin, variously 

 known as gum acaroides, yacka gum, and grass-tree 

 gum. Previous to the present war, by far the greater 

 part of the output of resin was consumed by Germany. 

 The purposes for which it was used are not known 

 with any certainty Inquiries made in 1910 led to the 

 explanation that it was used in Germany chiefly for the 

 manufacture of cheap furniture polish, and lacquer for 

 metal ware. It is not certain, however, that other n.ses 

 were not found for it. For instance, it is pointed out that 

 resin derived from a species of grass tree was one of 

 the earliest known sources of picric acil, a yield of 50 

 per cent, of which was said to have been obtained by 

 treating the resin with strong nitric acid. As picric acid is 

 one of the most widely usedof modern war exfilo.sive.^, and was 

 also formerly used to some extt'nt as a dyestuff, an impres- 

 sion has arisen that the resin was being ustid f >r picric -x-. d 

 manufacture, lii solved in methylated spirit the lesin g;ves 

 a spirit varnish oi a deep orange red colour. The core and 

 leaves of the grass tree are further believed to I e usci'ii in 

 the production of pulp for paper-making, though it is f.iuiii 

 somewhat difficnh to bleach 



