Mahch 2i, 1882.] 



KNOWLEDGE 



445 



which the food-particles assemble are not constant in their 

 position, and certainly do not possess any firm walls. 

 Although tho vacuole has not the structure of a vessel, 

 when food particles are assembled in its little open space, 

 it acts just like a real .stomach, and we must conclude that 

 fluids specially adapted for the work of digestion are pre- 

 pared l>y some of the visible granules and poured into it. 

 The nutritive products of the digestion ditl'use themselves 

 through the soft moist mass of the creature, and the useless 

 and used-up matters are excreted, in many species through 

 a definite anal aperture. 



The organs of these transparent and minute creatures, 

 when they have such, are often impossible to trace. Para- 

 mecia, and many others, for example, have a contractile 

 vesicle which expands as if filling itself, and then con- 

 tracts rhythmically, and it is supposed from the analogies 

 oflTered by larger creatures, that these vesicles, whose walls 

 are invisible, are connected with a series of tubes through 

 which fluids are impelled for both respiratory and excretory 

 purposes. 



However small may be tho creatures and their particles 

 of food, the composition of the latter, no doubt, resembles 

 that of higher animals, and has to be digested and assimi- 

 lated by a succession of similar processes. The microscopic 

 plants supply complex nitrogenous as well as starchy 

 materials, and the sarcode of the microscopic animal 

 resembles in ultimate composition the flesh of higher 

 creatures. 



The hay infusion is sure to supply some animalcules, 

 showing an advance of structure upon that of the Para- 

 mecium. A little oval creature, called Stylonichia, scarcely 

 so long as the largest Paramecium, is common, and has, 

 besides swimming cilia, some stiff bristles at each end, and 

 with these it can walk briskly over any substance. There 

 are many other animalcides similarly provided. The skin, 

 or integument, in some cases acts like the craVi's shell, or 

 the insect's external skeleton of the homy substances called 

 chitin. 



Let us for a moment consider the indications of nerve 

 power, without nerve structure, afforded by the creatures 

 we have noticed. First comes the perpetual movers. The 

 action of their surroundings upon their bodies causes the 

 molecules that do rudimentary nerve work to respond to 

 certain impressions by stimulating the cilia to their rapid 

 motion. The creatures that can be quiet when in full 

 vigour, and vary their movements with apparent purpose, 

 prefigure the voluntary actions of higher beings. The 

 little animals that can run, or swim, exercise something 

 that prefigures choice as to which set of locomotive organs 

 they employ. The reader may ask. Have they any sense of 

 pleasure in their busy and merry-looking existence ? To 

 this very natural query it is diflicult to give even a con- 

 jectural reply. Consciousness of existence could not be 

 conceived of them, but a feeling of pleasure may long pre- 

 cede any kind of know-ing, and we may gratify our own 

 sympathies, and not be far wrong if we deem them happy 

 in their little wav. 



NIGHTS WITH A THREE-INCH 

 TELESCOPE. 



By "A Fellow of the Eoyal AsTRoyoMicAL Societv."' 



PENDING the appearance in the eastern and south- 

 eastern sky of the spring and summer constellations, 

 we shall devote our present night to an examination of the 

 more strictly circumpolar ones. Our original intention 

 was to have gone over Virgo and the neighbouring region 



of the heavens. This, however, had, we now think, better 

 be deferred until that constellation approaches nearer to 

 the meridian during the working hours of the ordinary 

 amateur observer. Moreover, more than one of the con- 

 stellations we propose to in\estigate is now in a very 

 favourable position. First, then, let us turn to, perhaps, 

 the best known of them all — Ursa Major (Map, p. 3f<l), 

 now high in the north-eivst. We will begin by turning our 

 telescope, armed with a power of 1 20, upon f (Mizar). 

 Sharp -sighted people will detect with the naked eye a small 

 star (Alcor) in the immediate neighbourhood of Mizar. In 

 the telescope with the power specified, Mizar itself will be 

 seen to be double, and forming with Alcor the pretty 

 triple sj-stem shown in Fig. 2-'?. 



The pale-green of the small star of the pair will be noted. 

 a, Ursa> Majoris, examined with the very highest power at 

 the disposal of the observer will furnish an absolutely 

 crucial test of the excellence at once of his eye and tele- 

 scope. 2.3 ITrsa> Majoris is rather a wide pair, but interest- 

 ing from the difterent tints of its components. .57 is a pretty 

 pair for a similar reason, but very much closer than the 

 last ; it is unnumbered in the map. 65, a fine triple, 

 is also unnumbered, but may be recognised to the south 

 of \ on the boundary of Canes Venatici. y X^rsa- Majoris 

 lies in a fine field of stais. This constellation, we may re- 

 mark, swarms with double and triple stars, but as in a large 

 proportion of cases they are of less than the Gth magnitude, 

 the map takes no account of them, and it would be use- 

 less to give their co-ordinates, unless the observer's in- 

 strument were equatorially mounted. Several interesting 

 nebulas are to be found in Ursa !Major, but in the case of 

 the student for whom these papers are written, it can only 

 be by fishing. If he will conceive an equilateral triangle, 

 to be described with a and 2■^ Ursa? Majoris at the ex- 

 tremities of its base ; then, by sweeping about to the right 

 of its apex with the very lowest power he possesses, he 

 may hit upon the two nc-buL-e 81 and 82 Messier, 1° apart. 

 About 2" (four diameters of the moon) south-east of ft is 

 another nebula, 97 Messier, a pale circular object, looking 

 like the ghost of a planet. An imaginary line di'awn 

 diagonally from a through y Ursa^, and continued nearly 

 as far again, will strike upon IjIV. 43, an oval nebula. 

 Half-way, too, between /3 and 97 Messier lies Ii,lV. 40. This 

 will require some gazing at with so small an aperture. 



And now we will direct our telescope, armed with a power 

 of 160, to the Pole Star, which will be seen as depicted in 

 Fig. 24. 



This is sometimes alleged to be a test for a 3-inch tele- 

 scope, but it is not so. Dawes has seen the companion with 

 a 1 -S-inch object glass, and the eagle-eyed Ward, of Belfast, 

 with only 1 •25-inch aperture '. North-west of ;, Ursa; 

 Minoris will be found tt', a wide and easy object. 



Cassiopeia is one of the constellations through which 

 the Milky Way passes, and hence it affords innumerable 

 rich fields and clusters to repay the observer who sweeps 

 and fishes over it ; y, to begin with, lies in a fine field 

 of small stars. jj Cassiopeia, shown in Fig. 25, as 

 viewed with a power of 160, is a beautiful object, the 



