54 



KNOWLEDGE ♦ 



[Dec. 1, 1885. 



tion in tlieir inner o^^tline at that point wliicli is just 

 behind the antenna? -when thcj are in their most natural 

 position ; and it "tvould almost seem as thoiigh this limi- 

 tation to the extent of the visual organs were in some 

 way or other connected with the presence, immediately 

 in front of the spot, of the great black antennal scape, 

 which would certainly render useless for direct vision any 

 eyes situated immediately behind it. Yellow streaks 

 bound more or less of the outline of the eyes, and greatly 

 improve the appearance. 



On the top of the head we see three small, polished, 

 glassy-looking knobs, frequently of a ruby or yellow 

 colour, and arranged in triangular form. These are the 

 ocelli, or simple eyes, and their number and arrangement 

 are both very characteristic of the order Hymenoptera ; 

 we find the same little organs in bee.s, appearing like 

 tiny sjiarkling gems, half hidden by the hairs amongst 

 which they are imbedded. In the Ichneumon Plies, 

 Saw-flies, &c., we find a similar arrangement. 



Fig. 2.— Labium and 

 !j>, labial palpi ; nij), max! 



These are all 

 the natural position of the oro-ans 



maxillae ; 



the 



maxiUie of Wasp : /, labium 

 aiy palpi ; j), paraglossfe. 



the parts that are visible from above in 

 to get at the rest of 



complex ajiparatus of the head we must open the 

 Jaws, and then underneath we are introduced to a be- 

 wildering collection of organs (Fig. 2), as puzzling at first 

 sight as a piece of modern machinery. But a little 

 turning and twisting about, and examination from 

 various points of view, soon enables us to make out the 

 general plan and to see the relation of the parts to one 

 another. 



First, and just underneath the position occupied by 

 the mandibles when closed, are two thin, blade-like pieces 

 beset with hairs pointing forwards. These are the ter- 

 minal portions of the maxilla^, or secondary jaws, which, 

 as well as the mandibles, are capable of lateral movement. 

 Tracing them back to their point of attachment to the 

 head, we find that the basal part is of a somewhat more 

 substantial character than the terminal, and that at the 

 junction of the two parts, on the outer margin, each 

 maxilla carries a slender six-jointed appendage, the 

 maxillary palpus. When the maxillw are moved aside, 

 a single central organ, in-eviously partly covered by them, 

 comes into view ; in its front part it is thin, flat, and 

 band-like, but behind it is much thicker. This is the 

 labium, or so-called tongue. The flat portion is rather 

 deeply bifid in front, and carries two narrow organs, the 

 paraglossffi, attached to its sides, but not quite "i-eaching 

 the tip ; thus the free edge of the labium presents four 

 rounded divisions. Further back it carries two jointed 

 appendages, the labial palpi ; they are stouter than those 

 of the maxilla?, and are only four-jointed. It is this 

 tongue that the insect u.ses as a trowel in its plastering 

 operations, when it is manufacturing its nest. When 

 the mandibles are closed, they almost entirely conceal all 

 this mechanism, only the tips of the palpi being visible. 



From the above description it will be evident that a 

 wasp's head is not quite so simple an object as it might 

 at first sight appear; nevertheless, there is no great 



difficulty in making out for oneself all the above points. 

 Only two tools are necessary, a needle to open out the 

 mouth organs, and a hand-lens to examine the different 

 p?.rts. The examination is best conducted on an ampu- 

 tated head. The junction between head and thorax is so 

 slight that there is no difficulty in decapitating a wasp 

 (a dead one, of course !), and if a stout pin or the end of 

 a match cut down to a point be inserted in the small hole 

 that will be found at the spot where decapitation took 

 place, and the head be thus impaled after the fashion in 

 which the authorities in this country once upon a time 

 delighted to treat the heads of political offenders who 

 had suffered death for their indiscretion, the head may 

 be more conveniently handled and placed in any desired 

 position for examination. 



We must defer the consideration of the different 

 species of wasps till the next paper. 



MOVEMENTS OF THE PLANETS, 



Bv RicHArtD A. Peoctor. 



««.rij.^;j»r';lIIS month I give the movements of the 

 ve*^ four inferior planets. Mercury, Venus, the 

 Earth, and Mar.^, leaving to a later oppor- 

 tunity such explanatory diagrams as may 

 seem required to represent the motions of 

 Mars with regard to the earth. I give 

 also a map (taken from my zodiacal series, 

 showing the path of Mars during the opposition of 1886, 

 or really from November, 1885, to July, 18SG). Each 

 diagram explains itself. 



The following alterations should be made in the chart 

 of the solar system facing p. 8 ; (in the second edition of 

 our first monthly part, the chart was I believe cor- 

 rected): — Change 1889, outside the orbit of Neptune into 

 1885, and vice versd ; 1886 into 1888, and vice versd. In 

 other words, date the five points on the orbit of Neptune 

 from Jan. 1, 1885, to Jan. 1, 1889, the reverse way. 

 Alter Jan. 21 outside the orbit of the earth, to June 21. 

 With black ink hide the vertical straight line caused by 

 a split in the block. Note that the numbers round the 

 orbits indicate thousands of days from the supposed 

 starting-point in longitude 180°. 



MUSIC. 



l!v BaUONKSS V^iiN GolTRAU, 



Introduction. 



T is not, I believe, the object of this maga- 

 zine to publish the history of any jjarticular 

 subject, therefore it is not mj' intention to 

 give in these articles a record of dates of 

 when certain composers lived, what they 

 composed, when certain musical instruments 

 were invented, A:c. But I would like to 

 write about the old musicians and composei-s, also the 

 composers and musicians of our time, and, in fact, about 

 the study of music in general. 



1 have met persons who thought of music only as a 

 combination of different tones or sounds, and would bo 

 pleased to listen to a certain piece of music, because at 

 the moment those particular tones seemed to suit their 

 disposition ; but they would give not a thought to the 

 meaning of the music, for to them it was simply 

 a combination of sounds — meaning nothing in 

 particular. But what is Music ? It is indeed 



