HARDVVICKE'S SCIENCE-GOSSIP. 



83 



the scent was very faint on the grass and heather, but 

 strong in some very dirty lanes ; here dry dust held 

 the scent. At Gosport (an east wind prevailing) 

 several times, when the scent had been very cold 

 over plough and grass, it was strong along a strip of 

 shingly beach. This puzzled me for a long time, but 

 I think it was due to the pebbles being moist from 

 the encrusted salt, or their absorbing any moisture in 

 the air. Of course if it be an east wind with damp, 

 then the scent would be excellent. 



Effects of characters of food and water on fresh- 

 zvater fish. — No doubt an old story, but perhaps 

 worth recording. Near the Curragli Camp, Ireland, 

 was a large pond through which a very small stream 

 ran. The trout in it were splendid in colour and 

 flavour ; there was clear water and plenty of American 

 weed with caddis worms. Near Waterford, was a 

 bog with good-sized pools (from former excavations 

 of peat) and the river at times flooded it. These pools 

 were full of American weed, on which were herds of 

 caddis-worms. The water was perfectly clear, though 

 dark-looking in the pools from the colour of the soil. 

 The roach here, for example, had no trace of the so- 

 called muddy flavour. Indeed, on one occasion, salt 

 fish not being procurable, they were served up in 

 fillets with bread-crumbs, and a guest well versed in 

 the good things of the table thought he had been 

 eating soles. 



NATURAL HISTORY IN WINTER. 

 The Frozen-ovkr Ponds. 



PONDS and ditches ever swarm with living 

 creatures in various forms — even during the 

 hardest frosts just as in the warm months of summer. 

 The following notes on some examples of these beings 

 may be useful or interesting to your readers. 



]Many species of aquatic insects live through the 

 winter in a state of hybernation, burrowing in the mud 

 and among the roots at the bottom of ponds, &c. When 

 frosty weather sets in they are found snug in their 

 hiding-places, and whilethe water above is converted 

 into a vast sheet of ice they are beneath safe from 

 the cold. Then when the red winter sun sends forth 

 his warm rays these insects are seen through the ice 

 swimming about in search of the now scarce food. 

 They are chiefly beetles and the various species of 

 water bugs or boatmen (Notonectidre). The latter 

 especially are plentiful, they are found throughout 

 the whole winter and seem capable of sustaining un- 

 harmed a considerable amount of cold, although I 

 have frequently seen great numbers lying dead upon 

 the ice. They also congregate (and notably those of 

 the genus Corixa) among the water weeds, and are 

 easily obtained by taking up pieces of ice into which 

 are frozen large masses of aquatic plants and shaking 

 them over brown paper. Indeed, I find it remarked 

 by Mr. Westvvood that he has seen numbers under 



the ice, apparently torpid, grasping each other with 

 their legs. While treating of these insects it may 

 be well to mention that their semi-transparent elytra 

 form admirable microscopic objects for winter ex- 

 amination. They are easily mounted in Canada 

 balsam, not being liable to air bubbles. Under a 

 low power the surface is seen to be covered over 

 with beautifully-designed circular patterns. A variety 

 of good slides may be made any winter's evening 

 from one of these common insects. And I know of 

 no more productive situation for obtaining objects 

 for the microscope during the barren months than a 

 breach in the ice covering a vegetation-grown pond 

 or ditch. In an aquarium they are also interesting 

 creatures to watch ; I usually have a vessel of water 

 set apart for their own special benefit. It is most 

 amusing to watch their merry gyrations and to hear 

 the constant " tick ! tick ! " produced by their hard 

 heads striking against the sides of the vessel. Of 

 course they are obliged to come to the surface to 

 breathe, and frequently they float upon their side as 

 if they were dead. Water bugs — some of which are 

 extremely small, and others nearly an inch in length 

 — have the power of emitting a very sickening and 

 lasting odour. I find them very sensitive to light, 

 for on suddenly bringing a burning candle near 

 them at night, they immediately start from their 

 hiding-places and dash about as if at some material 

 foe. They soon however become accustomed to the 

 unnatural brightness. Nofonecta glaiica is a common 

 boatman often seen under the ice. The much- 

 dreaded Ranatra linearis, closely allied to the water 

 scorpion, is sometimes met with in a similar 

 situation. 



Passing- to beetles, the common whirlwig {Gyrinu 

 natafor), at all times a very social creature, is me 

 with in companies beneath an icy covering. In 

 summer the surface of ponds are often black with 

 their numbers : when any individual takes alarm the 

 entire colony scatters ; some of their black forms are 

 seen to disappear below, while others seek shelter 

 among the water plants. There are several species 

 of Gyrinida; that congregate on sunshiny morn- 

 ings where the ice is broken or melted. Of the 

 numerous other hybernating iDcetles may be named 

 the large Dytisciis inarginalis, often found beneath 

 the ice in a torpid condition. Agabus bipiisfiilatus 

 and ./. paliidosus are even more common in the same 

 situation. 



Of aquatic larvas that are plentiful, a good ex- 

 ample is that of the May-fly {Epieuiera vulgata) — • 

 a beautiful object for the inicroscope. The flat 

 plates attached by slender pedicles at each side of 

 the body, the gills of the larva, are well worthy of 

 examination. When the creature is not actually 

 swimming — and by the way, it swims by a lateral 

 vibrati<m of the body exactly like a tadpole — these gills 

 keep up a sort of to-and-fro motion. Through the 

 transparent body is seen the long alimentary canal 



