12& SCIENCE PROGRESS 



Weed seeds form a useful food for animals when they can be obtained in bulk, 

 and they are used either in their natural state or as cake after the oil has been 

 expressed from them. The seeds of poppy, charlock, and gold-of-pleasure 

 {Camelina sativd) all yield valuable supplies of oil, and a cake that is of much 

 feeding value. Black bindweed {Polygonum convolvulus) is closely related to 

 buckwheat, and the composition of the fruits is very similar, so that the weed 

 fruits have been utilised to replace buckwheat for feeding purposes. 1 The fruits 

 of cleavers {Galium aparine) are exceedingly hard, but have been used as food 

 for cattle when thoroughly ground.' 



Mulberry-leaves are not always obtainable for rearing silkworms, but they 

 can be replaced by comfrey {Symphytum officinale), dandelion and knot-grass 

 {Polygonum aviculare\ which are readily eaten by the caterpillars. Great claims 

 are made for comfrey, as German growers state that if the leaves are used for 

 food four or five crops of cocoons can be secured during one year, instead of the 

 single crop that is obtained when mulberry-leaves are fed. 



3. Fibres. — The utilisation of wild native plants for the provision of fibre 

 suitable for textile manufactures has not been considered very seriously until the 

 last few years, except in a few cases where local use has been made of occasional 

 species. Nettles ( Urtica dioica and U. urens) are the one exception to this, as 

 they have been exploited from very ancient times, though with the great modern 

 developments of cotton and linen manufactures they have fallen into disregard. 

 The ancient Egyptians held the secret of preparing fine white thread from nettles, 

 and this was largely used for weaving into textile fabrics. In some parts of Italy 

 nettle cloth has been woven till comparatively recent times, and in Siberia the 

 weed has provided the fibre needed for the manufacture of twine and rope, chiefly 

 for fishing-lines and cordage. 3 Some advance had been made during the last 

 ten years, as in 191 1 an Austrian firm devised a method of removing the gum from 

 the rough fibre, the resulting finished product being a pure bleached fibre which 

 was glossy, supple and flexible. The war, however, has given a considerable 

 impetus to the exploitation of this source of fibre, and so many improvements and 

 inventions have been carried out that it seems likely that, with judicious methods 

 of cultivation, nettles will prove a profitable crop. In 1916 the Central Powers 

 had developed the industry so far that nettle fibres were reported to cost 60 per 

 cent, less than imported cotton, and the War Ministries were using it for 

 manufacturing wagon-covers, tents, sackings, clothing materials, and even cloth 

 for military underwear. In Denmark the nettle yarn has been worked up with 

 wool, with satisfactory results. At first the warp was of wool, the woof of yarn 

 spun from nettle fibres, the resulting fabric being suitable for men's suits, as it was 

 not so soft as pure woollen cloth, though it possessed considerable strength. 

 Later on attempts were made to blend the wool and nettle fibres in the yarn, 

 as better results were expected from such a combination. 



Steps have been taken to organise the collection and cultivation of nettles, with 

 the result that by 1918 it was estimated that 23,000 hectares (= 9,292 acres) would 

 be under nettle cultivation in Germany, with an estimated yield of 175,000 

 metric cwt. of fibre. The cultivation of nettles has also been encouraged in 

 Hungary, a special company being formed to further the work. The plants 

 will grow well on ground that is of little agricultural value, and in some plantations 



1 Hogg and Johnson, ibid. Landw. Versuchs-stat. 78. See Journ. Board 

 Agric. vol. xix. pp. 676-7. 



1 Bernatsky, J., 191 5. See Rome Bull. vol. vii. pp. 245-6, 1916. 

 3 Hogg and Johnson, ibid. 



