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Fish Culture on the Lea.—It may prove interesting to many of your readers, especially Waltonians, to know that there is an establishment for the cultivation of fish at Ponder's-end, on the river Lea. It is certainly on a smaller scale than the one at Hampton, yet everything is in. a perfect state, and some thousands of salmon and trout ova are to be seen in their different stages of development. The proprietor is at all times willing to permit inspection. I was much gratified myself, and have no doubt so will others who take an interest in piscicultare.—Daily Telegraph.

A Good Pike.—On the morning of May 9th, a pike was caught in Grasmere Lake, weighing 23½ lbs. Its length was forty-two, and extreme girth twenty-one inches.—Edwin Green.

Salmon in Australia.—At a recent meeting of the council of the Australasian Acclimatisation Society, a letter from Mr. Green, of Badger Creek, was read, stating that the salmon continue in the best of health. Mr. Green also forwarded a memorandum of the temperature of the creek, by which it appears that on the hottest day, when the temperature of the air at noon was at 95°, that of the creek was only 61°; thus proving that from this source no danger is likely to arise that will in any way imperil the undertaking.—R. T.

Reproduction of the Eel.—In reply to "E. B.," no competent ichthyologist has the slightest doubt that cols are produced from deposited ova, after the fashion of most fish. If "E. B.'s" friend will open any eel, at almost any time of the year, he will see two beautiful white fatty fringes running nearly the whole length of the body, one on each side; these are the sexual organs. If a portion of the fringe be submitted to microscopic examination, it will be seen that it consists of a multitude of round or oval grains, very minute, imbedded in a mass of fat or oil globules. The oval grains are the eggs of the female fish, the round ones are the milt of the male. These latter are extremely minute: the ova are readily discernible by the naked eye, and may be seen by shaking or breaking up a portion of the fringe upon a glass slide with a little water. The author to whom we are chiefly indebted for having clearly demonstrated the oviparous nature of the eel is M. Reinh. Fr. Maur. Hohnbaum-Hornschuch, in his treatise, written in Latin, "De Anguillarum Sexu ac Gencratione." The treatise, which bears the date of 1842, is, I believe, rare. I possess a copy in my library. It has one plate, with accurate figures illustrating the sexual organs. If your correspondent is interested in eel-lore, he may perhaps care to read an article of mine on this subject in the "Quarterly Review," No. 229, January, 1864.

Brücke's Lens.—I make frequent use of this valuable little arrangement, manufactured (and sold for fifteen shillings) by Messrs. Paetz & Flohr, opticians, of No. 14, Under the Lindens, Berlin. It consists of a one-slide achromatic telescope measuring when closed about three inches long, and an inch and a half in diameter, and its use is to magnify small objects in aquaria, when they cannot be closely approached or removed. Under these circumstances, and at distances varying from fifteen to eight inches, this instrument produces the same amount of amplification as is obtained by an ordinary pocket-lens at distances of from one inch to half an inch.—W. Alford Lloyd.

American Water-weed (Anacharis alsinastrum).—This plant, commonly known as the "American water-weed," was first noticed in England in 1842. Since then it has spread rapidly, and in many counties has become almost ruinous, choking up water-courses and canals, and threatening, in some parts, a universal stoppage. It is found, also, very commonly in ponds and ditches, where it soon obtains a similar mastery. The best eradicators (if introduced before the plant has become too powerful) are said to be swans. After flowering, however, it appears to decline of itself: it is also much affected by severe frost. One reason of its enormous increase in Britain is, probably, that the individuals are all of the feminine gender, since it is a matter of common observation that plants prevented by any casualty from ripening seed, and supplied at the some time with plenty of nutriment, are prone to extra vegetative development. It should not be overlooked, that although in one respect a hateful incumbrance, the Anacharis produces good sanitary results; many a ditch that was offensive before having become clear through its purifying influence. Like others of the family, it makes a becoming and cheerful aquarium plant, and, preserved in a parlour, often blooms freely.—Grindon's British and Garden Botany.

Plants.—What are the most suitable plants for an aquarium? Not the oar-weeds or tangles; for though young specimens have an attractive appearance, they will not live long in captivity; they presently begin to decay, and slough off in slimy membranous shreds, filthy to look at, and hurtful to the living creatures. The Fuci live pretty well, but their sliminess and ugliness are fatal to their pretensions. From the red and the green orders we must make our selection. The pieces of rock to which the plants are attached should be as clean as possible. All adhering sponges, in particular, should be carefully scraped off, unless they are wanted for immediate examination.—Gosse's Aquarium.