HARDWICKE'S SCIENCE-GOSSIP. 



i77 



organ is "short and membranous, and terminated 

 with two large lobes. These are seen to be traversed 

 by a number of air-tubes of a rather peculiar structure, 

 all radiating from two principal tubes, one to each 

 lobe. Generally the air-tubes, or tracheae of insects, 

 are kept in shape by a spiral thread, between two 

 layers of which they are composed, but in the air- 

 tubes of the proboscis the place of the spiral thread is 

 taken by a number of incomplete rings, called false 

 tracheae. These incomplete rings look something 

 like the ancient torque, or, to speak more familiarly, 

 like a horseshoe. The open part of each ring is 

 downward, and the result of this structure is that 



developed ; it then consists of an oval-shaped form, 

 and is contained in a thin membrane. One end of 

 this body is semi-opaque, and is the first clearly- 

 defined indication of the future egg it has been my 

 lot to observe (as I have not yet been able to obtain 

 the pupa; stage). The other half is translucent, and 

 contains about sixteen small bodies of a somewhat 

 circular form, each containing a central nucleus. 

 Attached to this end are two small sac-like bodies, 

 also semi-opaque, likewise covered with a thin, and 

 apparently structureless, membrane. The succeeding 

 stage is reached when the egg appears in the cylin- 

 drical form, but has still attached to it at one end 



Fig. 109.— Ova taken from grub, first stage of Fig. no. — Partly de- 

 development. X 200 diams. ; average size veloped egg. X 46 

 •004. diams. ; '03 long. 



'kam 



Willi 1 , 1 



mm 



)\\ 



I MS 



Fig. in. — Perfect egg. 

 X 46 diams. ; "05. 



"I 







v-- ■••''• '•'' . •' ■' „>--" ■' .'• '.■^"v**/*.-"" . •■;. 



■ '- ~lS?-~.~ ;' - 

 , ^--N^ ------- ; ■ .^W^//*/"* ■ 



Sii •••■ ' 



Fig. 113. — Small portion of empty egg-case, 

 showing the general arrangement of reticulation. 



-a 



Fig. iT2. — Further 

 stage. X 46 diams. ; 

 •04, a, *oi. 



they form a sort of strainer through which the liquid 

 portion of their food is passed." It is rather rapid 

 in flight, easily disturbed, and, on account of its 

 colour, not very easily seen, unless closely looked for. 

 On dissecting a grub fully-grown, a mass of matter 

 is met with which, to all appearance, looks like ova 

 in an embryonic state. It comes out in a flat plate- 

 like form, and under a power of 300 diameters is 

 seen to consist of a large number of separate cells, 

 closely packed side by side. The further development 

 may be traced in the perfect .insect more clearly by 

 taking them in different conditions. The next stage 

 is reached when the egg can be seen to be partly 



three cells, the one adjoining the egg being the 

 largest, but each may be seen to contain the small 

 bodies above described, the office of which is doubt- 

 less the formation and nourishment of the egg. 



The perfect form is now reached, the reticulations 

 are visible, which consists of two distinct descrip- 

 tions. At first sight the egg appears to be simply a 

 network of elongated cells, but if a high power be 

 used, these appear to be formed by the thickening 

 of the outer covering, and the spaces between will be 

 seen to be very finely marked with small circular dots. 



From the region of fact I would for one minute 

 turn aside to that of speculation, and ask what object 



