April, igo6.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



407 



grouped under three heads — winged fruits and seeds ; 

 plumed fr ^'^ and seeds; " powder seed," or dust-lil^e, as 

 orchid .seed,'" tern spores, &c. Winged seeds or fruit is dis- 

 persed at the slowest rate, and is unable to cross a wide 

 expanse of sea ; the plumed type is well adapted for rapid 

 transit over open country, but is checked by forest areas, 

 whereas " powder-seed " is dispersed most rapidly and to the 

 greatest distance. 



The greatest observed distance travelled by the winged 

 fruit of a forest tree, tihorea leprvsula, was 100 \ards. From 

 this it is calculated that this plant could, under the most 

 favourable circumstances, only spread 300 yards in lou years, 

 and that it would take one and a half million years to spread 

 from the Malay Peninsula to the Philippines, supposing a 

 land connection existed. 



Smvit. 



Smut is the name used by farmers and gardeners to 

 designate certain kinds of fungi belonging to the genus 

 Ustilaqu, which form black powdery masses in the ears of 

 oats, barley, wheat, and various other grasses ; also in the 

 anthers of some flowers, as Scilla, Lychnis, &c. In the case 

 of oats infection can only be effected when the plant is in 

 the youngest seedling stage. The fungus spores are dis- 

 persed by wind, and retain their vitality until the following 

 spring, when they germinate on any decaying vegetable 

 matter present in the soil, usually manure ; the germ-tubes 

 pierce the delicate tissue of the oat plant immediately after 

 gerniin.ition. After infection the mycelioma of the fungus 

 grows up along with the oat plant, without producing any 

 injurious effect, until the flowering stage, when the fungus 

 enters the ovary and produces a black sooty mass of spores 

 in place of the fruit. Maize, or Indian corn, it has for some 

 time been known, can be infected at any point where very 

 young tissue is present, but with this exception it has up to 

 the present been considered that all other cereals could only 

 be infected during the seedling stage, as described for the 

 oat. Brefeld, a German botanist well-known for his many 

 and important contributions towards the life-history of fungi, 

 has recently been studying the smuts attacking cereals, and 

 has proved by experiments that the smut spores of barley 

 and wheat can only infect the plant through the flower. 

 The spores alight on the stigma, where they germinate and 

 penetrate the ovule, remaining there until the following 

 season. When such infected seed is sown, the fungus grows 

 up along with the plant, and eventually produces smut in 

 place of grain in the ear. 



In some instances the fungus spores are dispersed by 

 wind, in others they are carried to the stigmas along with 

 pollen by butterflies. In the case of aquatic grasses, the 

 fungus spores are conveyed bv water. 



This discovery adds wheat and barley to the already con- 

 siderable number of economic plants of primary importance, 

 whose most destructive enemy in the form of a parasitic 

 fungus, can be conveyed from one district or one country to 

 another in the form of mycelium present in the seed, tuber, 

 bulb, &c. In this condition detection is impossible, and the 

 danger of introducing disease into a new district consider- 

 ably augmented. 



Mosses as Storers of Water. 



ExperimcnK conducted by .\. Csriiy show lli.it some 

 abundant kinds of mosses, as llypniLm, IJiiranum, 

 Sphaiinum, &c., absorb about six times thtMr own weight of 

 water in less than a minute, and require seven days wherein 

 to give it all up again. This function is probably of much 

 service on st'-ep slopes, where an excessive rainfall if not 

 checked would prove very destructive, and, further, by slow 

 liberation of water the humidity of the air is, to some 

 extent, secured. 



CHEMICAL. 



By C. AiNswouin Mltciikll, li.A. (Oxon.), F.I.C. 



A Physiological Test for Copper. 



I !■ lia-- Inqucnlly been noticeil llial the lra\es of plants that 

 have been treated with a solution of copper sulphate show 



abnormal deposits of starch. This is evidently due to the 

 poisonous action of the metal upon the enzyme diastase, 

 which converts the starch of the plant cells into sugar, and 

 it has been found by Herr Ewert that a minute trace of 

 copper sulphate (o.ooo(;o5i gramme) is sufficient to produce 

 this paralysing effect upon diastase left in contact with a 

 very dilute solution of starch. On this fact he has based 

 a very delicate physiological test for traces of copper. A 

 plant watered with a dilute solution of copper sulphate at 

 once begins to deposit the starch, and the latter can easily 

 be recognised by the characteristic blue coloration that it 

 gives with iodine. The leaves of a plant thus treated give 

 the reaction after about an hour and a half, whereas the 

 leaves of a normal plant do not turn blue on treatment with 

 iodine. 



Tlie Origin of Fusel Oil. 



l""usel oil, long regarded as an objectionable waste pro- 

 duct in the manufacture of spirit, has latterly become an 

 unportant article of commerce, owing to its use as the basis 

 of a solvent for guncotton, in the manufacture of smokeless 

 powders, and for artificial fruit essences, and experiments 

 nave been made to find a means of obtaining it in larger 

 quantity. The most important discovery in this direction 

 is that made by Dr. Ehrlich, of Berlin, who finds that, con- 

 trary to the generally accepted view, fusel oil is formed, 

 not by the action of certain bacteria upon sugar, but by 

 the yeast itself acting upon nitrogenous compounds, such 

 as the amido acids invariably present in decoctions of malt. 

 It transforms these compounds into amyl alcohol (fusel oil), 

 and ammonia, the latter being utilised in building up the 

 protein of its own cells. Dr. Ehrlich also finds that it is 

 possible so to arrange the relative proportions of yeast and 

 sugar that any given amount of the amido acid (leucine) 

 may be added to the fermenting liquid and converted into 

 fusel oil, which may subsequently be separated from the 

 main product (ordinary alcohol) of the fermentation. An 

 abundant source of leucine is found in numerous bye-pro- 

 ducts rich in nitrogen, such as horn shavings and the waste 

 liquors from the manufacture of glue, and this discovery 

 of Dr. Ehrlich indicates the possibility of establishing an 

 important branch of industry in connection with the manu- 

 facture of spirit. 



EaLrth-£aters and their " Food." 



Eaters of earth have been known for centuries, and to 

 this day are found in Guinea, Senegal, and New Caledonia, 

 and in various parts of .South .America. The French 

 naturalist, .M. Courty, who recently explored the high table- 

 lands of Bolivia, states that the Indians there are very 

 fond of a paste of clay, which they mix with coca leaves ; 

 but as a rule the earth-eaters take the clay by itself in the 

 form of little pellets dried in the sun or over a slow fire. It 

 has been asserted by certain explorers that the particular 

 earth eaten has really some nutritive value. Humboldt, 

 for instance, writing in 1800, mentioned that the Indians 

 (■n tlie banks of the Orinoco consumed as much as cue and 

 a half pound per day of earth, "qui parait etre nourissante." 

 Two specimens of these earths exhibited in the last Paris 

 Exhibition have recently been examined by M. Balland. 

 One of them, from Gabon, was a light-grey powder, con- 

 sisting of about 95 per cent, of silica, about 4 per cent, of 

 iron oxide and alumina, 0.5 per cent, of water, and traces 

 of magnesia, etc. The other specimen, from New Cale- 

 donia, was of a yellow colour, and contained about gS per 

 cent, of silica, 0.4 per cent, of magnesia, and o.S per cent, 

 of water, with traces of sulphate but was free from iron, 

 alumina, or lime. .\ New Caledonian product, analysed in 

 1801 by Vaquelin, contained 18 per cent, of iron oxide and 

 J per cent, of copper, the remainder being chiefly silica 

 and magnesia. It is thus evident that these earths have 

 no value as food, and may even be injurious when con- 

 taining copper, although it has been pointed out that they 

 inay have a negative value as .1 supplement to a diet devoid 

 ot woody fibre, c.<i., lish, their mechanical action aiding in 

 ihe tlivision of the food and thus indirectly promoting 

 digestion. 



