'/6 



KNOV/LEDGE ♦ 



[Jan. 1, 1886. 



rosctteF, as shown in Fig. i. Otliers are larger, of 

 which a sjiocimcn is given in Fig. 5, taken from the tail 

 end. Under a high power, minute, dot-like projections 

 are seen, but I could detect no openings, and do not know 

 what they are. Mr. Buckton dues not mention them. 



I have not been fortunate enough to see the cotton- 

 down exuded, or to find the organs exuding it. 



Putting some bits of twig covered with the creatures 

 in a box with a glass lid facilitated watching them. They 

 could not have obtained much nourishment, as the twigs 

 soon dried up, but the young were produced in great 

 numbers. Not one, however, put forth a particle of the 

 cotton stuff. 



Ffe. i. 



(x 320.) 



Fig. 5. 



Like the rest of their tribe, they are difficult to dissect. 

 The operation is facilitated by a little glj'cerine, and 

 more can be done in a drop of methylated spirit than in 

 plain water. The tracheal system is well developed, and 

 some of the larger vessels are easily distinguished 

 amongst the miscellaneous matter that comes out when 

 s, specimen is squeezed in a water drop. It is then easy 

 to pick out some trachea^ with a mounted needle. 



Besides the apple-tree plague, other species attack 

 elms, dogwoods, Arc, and, on the whole, they are among 

 the worst of the insect plagues. America is credited 

 with their origin, and hence they are often called 

 "American Blight." Like other aphides, they chiefly 

 multiply by viviparous broods. The males occur late 

 in the se.ason, and are not often seen. They are born 

 with a rostrum, but Mr. Buckton observes, " the rostrum 

 would seem to disappear at the subsequent moult. The 

 sex is finally blind as well as mouthless." The oviparous 

 female is also described as destitute of a sucking organ. 

 The viviparous females occur in a winged form as well 

 as in a wingkss one, and Lichtenstein, cited by Buckton, 

 says they swarm in September in the south of France. 



The orgi.nisation of these creatures seems above the 

 necessities of their way of life. As individuals they 

 deterior.ite as they pass from infancy to the adult stage. 

 Any action of rndimentary intelligence ceases when they 

 have fixed their mouths in a good place, and penetrated 

 to the sap vessels. They have then nothing to do but 

 suck and bring forth numbers of their kind. 



The scientific name of the section of aphides to which 



the Cotton Bugs belong is Schizoneurina?, from the Greek 

 schizo, to cut, and neuron, a nerve. It refers to the 

 furcations of the veins in the winged forms. The 

 Cotton Bug of the apple is Schizoneura lanigera (wool- 

 bearing). S. ulmi attacks the elm. 8. lanuginosa forms 

 gall-like masses at the ends of the twigs of Uimus 

 campestris and Z7. suberosa, which are densely hairy 

 (Buckton). S. corni assails dog-wood. 



THE STORY OF CREATION. 



a plain account of evoldtion. 



By Edward Clodd. 



III.--PISTRIBUTIOX OF MATTER IN SPACE. 



JATTER, as explained in the foregoing 

 .section, is both visible and invisible, 

 ponderable and imponderable. In its 

 ponderable form it is distributed through- 

 out space in bodies of varying densities ; 

 in its imponderable form as ether it fills 

 the intervals between the particles com- 

 posing those bodies, as also the vast intervals between 

 the bodies themselves. The mo.st important of these — 

 as the sand by the seashore, innumerable — are the 

 "fixed" stars, so called from having no apparent motion 

 of their own, although, in reality travelling at enormous 

 velocities. Each of these, unless it be an extinct, burnt- 

 out sun, shines by its own light, and is probably the 

 centre of a system of planets with their satellites or moons, 

 and other bodies, as is our sun, which is itself a star. " One 

 star differeth from another star in glory." Not, speaking 

 broadly, in the stuiJ of which all are made, for the light 

 thrown by the spectroscope on the chemistry of the 

 heavenly bodies has revealed their general identity of 

 structure. No matter how distant the star, so long as 

 the light emitted is strong enough ; broken on prisms, it 

 reveals through its spectrum net only what elements are 

 present in the glowing vapour, but even the direction of 

 the star's motion, i.e., whether it is receding from or 

 approaching our system. The nearest fixed star is Alpha 

 Centauri, the annual pr.rallai of which (that is, the 

 apparent change of position as seen from opposite points 

 of the earth's orbit) is nearly one second of arc, giving a 

 distance of twenty millions of millions of miles. Its 

 light, travelling 186,000 miles per second of time, there- 

 fore, takes nearly three years and a half to reach us, and 

 so vast is the interval that, viewed from this star, our 

 solar system appears as only a point in space. 



The differences between the stars are in their sizes, 

 their brilliancy or magnitude, and their colours, this last 

 giving some clue to their stage of development. For 

 there are stars young, middle-aged, old and decrepid ; 

 and there are stars cold and dead, radiating no energy, 

 and whose existence can be known only by their influence 

 under the force of gravitation upon other bodies. 



The astronomer has not arrived as yet at any certain 

 conclusions regarding the general distribution of matter 

 in space. But the combinations, as seen from our system, 

 are as varied as they are complex. Besides double and 

 multiple stars — their apparent nearness often being due 

 to their Iving in nearly the same straight line from our 

 system — there are the constellations, many of the names 

 of which are relics of that animistic stage in man's belief 

 when everything was personified. There are star-clusters, 

 light, cloudy-looking patches, made up of suns which, 

 from our point of view, lie densely packed together in 

 galaxies nitmberless as the bodies that compose them. 



