Sept. 1, 1S6S.] 



H A RD W ICKE'S SCIENCE-GOSSIP. 



211 



MICROSCOPY. 



The Celeey-leae Miner (TepAritis onopor 

 dinis). — This has been a jubilee year with all the 

 insects that prey upon our cultivated plants ; the 

 weevils and beetles, wireworms, flies, grubs, aphi- 

 des, and caterpillars have had it all their own 

 way. My cabbages are stripped to the stumps, my 

 cucumbers and marrows are drilled through at the 

 roots, my potatoes bored full of holes, my apples 

 are all droppiug from the trees, my turnip-tops are 

 riddled as though ten thousand hedge-poppers had 

 been blazing away charges of snipe-shot over the 

 beds, and the leaves of my celery plants are all 

 over blisters and brown patches. Opening one of 

 these blisters the other day, I found therein a green 

 maggot about one eighth of an inch in length, with 

 a broad and flatfish tail, from which his round, 

 tight-looking body tapered to his sharp-pointed 

 head, or rather mouth — for head, according to our 

 common notions of heads, he had none. There he 

 was between the two paginae of the leaf burrowing 

 tunnels, and feasting on the juicy cellular paren- 

 chyma in which his speckled-winged mother had 

 deposited him in the form of an egg last April. 

 These creatures, the larvae of the fly named above, 

 are swarming in myriads. Why don't they confine 

 their attention to the common cotton-thistle from 

 which they get their ugly names, instead of run- 

 ning riot amongst our celery and parsnips. I have 

 got rid of these invaders and saved my celery 

 trenches by pinching the blisters whenever they 

 appeared, in accordance with the advice of Mr. 

 Curtis, contained in his " Earm Insects," in which 

 interesting work a full description of Tephritis, 

 amongst many others, with beautiful coloured 

 drawings of the. insect in all its stages, will be 

 found. This larva being very thin-skinned and 

 almost transparent, is a capital object for young 

 microscopists, to whose notice I specially commend 

 it. Placed in the live-box, and pressed just suffi- 

 ciently to keep it from wriggling out of the field, the 

 body being flattened a little by the operation, so as 

 to keep the viscera pretty evenly in the plane of the 

 focus without impeding their natural play, one can 

 hardly wish for an easier and more beautiful living 

 illustration of the internal mechanism of insecta in 

 the larva stage. With a two-thirds objective the 

 muscles of the never-resting mouth show through 

 the smooth filmy skin like blackened threads while 

 they twitch and work. Nothing in the way of an 

 eye is discernible, though probably the rudiments 

 thereof are present, though undeveloped. Our 

 larva— spending his working life inclosed in shafts 

 and caves of his own excavating, and never going 

 beyond the boundary-walls of the epidermis of the 

 leaf — has no need of eyes at present. The dorsal 

 vessel is so transparent, and its walls are so fine and 



delicate, that its structure would remain almost 

 invisible, its very presence undiscoverable, but for 

 its rhythmical pumpings. The little beadlike 

 bubbles of the chylaqueous fluid can be observed 

 chasing each other ; the digestive apparatus looks a 

 little indistinct. The great stores of fat which the 

 fellow is so busily laying up in oily-looking globules 

 confined in the finest of network, arranged in sym- 

 metrical rows along the edges of his back (I speak 

 of his round back when flattened out by the glass 

 of the live-box) show out well. These form the 

 preserved provisions, out of which, during the next 

 stage, the pupa will manufacture itself into the fully- 

 developed imago— the pretty little fly with barred 

 wings. But the breathing! apparatus is the chief 

 attraction; on either side of the dorsal vessel or 

 elongated heart, runs a maiu tracheal tube silvery 

 and shining, and not unlike a bright new harp- 

 string, sending off its secondary branches, which 

 again subdivide and ramify ad infinitum, till they 

 become invisible even under a power of seventy-five 

 diameters, carrying everywhere throughout the 

 viscera, and even to the free floating globules of 

 the blood,— for blood it is, though it isn't the 

 fashion to call it so, — the vivifying marvellous agent 

 oxygen. Here in these lowly creatures we see the 

 air carried to the blood, while higher in tlie scale we 

 find the blood carried to the air. After a good 

 general survey has been taken with the two-thirds, 

 it is worth while to flatten the object as much as it 

 will bear without bursting, and to examine it with 

 the quarter-inch, when the spiral arrangement of 

 the muscular fibres of the tracheae becomes beauti 

 fully distinct, and the teeth or curved horny plates 

 of the very small and restless mouth become 

 visible. — /. Y. H., Bury Cross, Gosport, 10th Aug., 

 1S68. 



Mosquitoes. — Now that the subject of mos- 

 quitoes has insinuated itself into the metropolitan 

 mind, and the lancets of mosquitoes are said to have 

 insinuated themselves into metropolitan bodies, it 

 may be apropos to allude to a paper on these 

 insects which appeared in an early number of the 

 Quarterly Journal of Microscopical Science, entitled 

 " Auditory Apparatus of the Culex Mosquito, by 

 Christopher Johnston, M.D." vol. iii. (1S55), page 

 97, with plate. 



Salsify Pollen. — Wherever it is cultivated, the 

 Salsify is now in flower. Let all who admire pollen 

 as a microscopical object, at once secure the pollen 

 of this plant (Tragopogon porrifolius) ; and at the 

 same time, although the chances are less, endeavour 

 to procure the still more beautiful pollen of the 

 Scorzonera {Scorzonera Hispanica), at one time 

 common, but now rare, in our kitchen gardens. The 

 pollen of all composite plants is good, but these 

 are amongst the best. 



