160 



HARDWICKE'S SCIENCE -GOSSIP. 



The maxillary palpi originate from the maxillis 

 just described. They are very prominent objects, 

 being relatively much larger than the same organs 

 in most other insects. They are directed forwards 

 and slightly upwards, and consist of four joints 

 each, the last being nearly as long as the three tii-st 

 together, and of a more membranous character ; it 

 is covered with minute chitinous spines, arranged 

 in groups of four or five. I suspect that in these 

 terminal joints of the palpi, the chitinous substance 

 is imperfectly deposited, only occupying the centre 

 of each cell, where it assumes the form just stated, 

 and leaves the edges transparent, thus giving a 

 somewhat membranous appearance to the joint. 



The pharynx is the last of the organs with which 

 I have to deal. It is connected by a short membra- 

 nous tube with the cavity of the mouth, and extends 

 through the brain to the back of the hetd, where it 

 is continuous with the oesophagus.* A section 

 near the fore part shows a double wall, or, as I 

 prefer to regard it, one continuous integument bent 

 in upon itself on the upper surface, thus forming a 

 deep groove, from the bottom of which a pair of 

 muscles arise which are inserted above in the in- 

 tegument of the head between the eyes. The pos- 

 terior portion, however, exhibits a section mate- 

 rially modified, which somewhat resembles the letter 

 Y, the extremities of which are curiously folded 

 over. The horny substance being thin and yielding 

 along the line of the folds, allotvs of the central 

 cavity being very much enlarged by the action of 

 four muscles, two of which corresponding to the 

 two already alluded to on the anterior portion, 

 arise from the superior groove or fork of the Y, and 

 are counterbalanced by two others arising from the 

 lateral portions of the same, all four being inserted 

 in the integument of the head. The main design 

 of this arrangement is, I think, obvious, though I 

 cannot state it in detail. The (perhaps alternate) 

 action of the muscles attached to the pharynx and 

 the roof of the mouth, evidently effects the ascent 

 of the fluid aliment upon which the insect feeds, 

 the propulsion of which into the (Esophagus is 

 brought about by the elasticity of the walls of these 

 two cavities. 



With regard to the modus operandi,! \^ould 

 observe, in the first place, that a sufficient number 

 of specimens should be obtained,— thirty or forty 



• This connection of the pharynx with the cavity of the 

 mouth on the one hand, and with the oesophagus on 

 the other, together with its evident similarity of function, 

 induce me to regard it as tbe organ described by Mr. Lowne 

 under the same name in the Blow-fly ; but I And it difficult 

 to understand how it is, that while in the insect just named 

 it is closely connected with, and indeed described by that 

 gentleman as formingpart of the basal joint of the proboscis, — 

 viz., the third or niRxillary segment; in the insect before us it 

 seems totally dissevered from any such union, occupying as 

 it does the globular cavity of the head, and far removed from 

 the maxillae altogether. 



will not be found too many, as some will probably 

 be spoiled in first efforts, before much is learnt 

 from them.- When the object is large, it may be 

 pinned to a loaded cork at the bottom of an empty 

 sardine box, improvised; as a dissecting-trough, as 

 advised by Mr. Gedge (see S.-G. for August, 

 1866), and filled with water just suSicient to 

 cover the object. It this be too small, however, 

 as in the present case, to admit of the use of pins, it 

 will be better to place it in a shallow cell or even 

 in a drop of water on the surface of a slide. 



The magnifying power employed need not be 

 very great ; for most purposes I have used a lens 

 removed from an old telescope, but where greater 

 amplification is needed, I have used the inch objec- 

 tive of my microscope, which answers the purpose 

 very well. A few specimens should always be ex- 

 amined in a fresh condition just killed, which is 

 easily done by placing them for a few seconds in 

 spirits of wine. When this cannot be done, they 

 should be allowed to remain in the spirit for the 

 purpose of preservation; the appearance of the 

 tissues however is much altered, and by no means 

 improved by the process. Eor examining the in- 

 tegument it will be frequently desirable to soak the 

 insect for a few days in liquor potassse to remove aU 

 the soft parts. Sections should be made in difTer- 

 ent directions, and the parts teased out with needles ; 

 any skill which the operator may possess in drawing 

 should be freely made use of to delineate each por- 

 tion as soon as it is satisfactorily made out ; indeed, 

 some effort to do this is indispensable in order to 

 retain information once acquired, or to communicate 

 it to others. If any further requisite be necessary, 

 I can only sum it up in two words—" patience " 

 and " perseverance." A. Hamsiond. 



4, Neptune Terrace, Sheerness. 



MICROSCOPY. 



Mounting in Glycekine Jelly (p. 88). — 

 Though I have sometimes found this medium useful 

 for small objects without a cell, with larger ones 

 and cells I cannot speak so well of it. The jelly, 

 after a year or so, shrinks, bending the covering 

 glass, and if the mount is of any size, the jelly is 

 apt to crack, unless air can get in at the side. 

 I lately had to turn upwards of a hundred slides 

 out of my cabinets through this fault ; fortunately 

 I had been cautious enough to mount only a few, 

 and only common specimens. — E. P. P. 



A Problem in Mounting (p. 89). — I have 

 not unfrequeutly seen the phenomena Mr. Laing 

 speaks of, and, like him, I have watched the apparent 

 air-bubble develop. I once spoke to one of our 

 leading mounters, who told me he had to contend 



