June 1, 1865.] 



SCIENCE-GOSSIP. 



141 



FISH TATTLE. 

 EisH CuLTUEE ON THE Lea. — It may prove 

 interesting to many of your readers, especially 

 Waltonians, to know that there is an establish- 

 ment 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 pisciculture.— Z'rtZ/y Telegraph. 



A Good Pike. — On the morning of May 9th, a 

 pike was caught in Grasmere Lake, weighing 

 234 lbs. Its length was forty-two, and extreme 

 girth twenty-one inches. — Edtoin 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 memo- 

 randum of the temperature of the creek, by which it 

 appears that on the hottest day, when the temper- 

 ature of the air at noon was at 98", that of the creek 

 was only 61° ; thus proving that from this source no 

 danger is likely to arise that will in anyway imperil 

 the undertaking. — R. T. 



REmcBUCTiON OF THE Eel. — -In reply to 

 " E. B.," no competent ichthyologist has the slightest 

 doubt that eels 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 wiU 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 wiU 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. Eeinh. Er. Maur. Hohnbaum- 

 Ilornschuch, in his treatise, -nTitten in Latin, "De 

 Anguillarum Sexu ac Generatione." 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 Ilcview," No. 229, 

 January, 186 i. W. Houghton. 



WINDOW GARDENS AND AaUAEIA. 



Brucke's Lens.— I make frequent use of this 

 valuable little arrangement, manufactured (and sold 

 for fifteen shillings) by Messrs. Paetz & Elohr, 

 opticians, of No. 14, Under the Lindens, Berlm. 

 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 mag- 

 nify small objects in aquaria, when they cannot be 

 closely approached or removed. Under these cir- 

 cumstances, 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. Alforcl Lloyd. 



American Water-weed {AnacJiaris alsinastrum). 

 — This plant, commonly known as the "American 

 water-weed," was first noticed in England in 

 1812. 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 decli:ie of itself: it is also much afl'ected 

 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 same time 

 with plenty of nutriment, are prone to extra vege- 

 tative 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 Bo- 

 tany. 



Plants. — What are the most suitable plants foi- 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. Tlie ¥uci live pretty well, but their sli- 

 miness and ugliness are fatal to their pretensions. 

 Erom the red and the green orders we nuist make our 

 selection. The pieces of rock to which the plants 

 are attached should be as clean as possible. All ad- 

 hering sponges, in particular, should be carefully 

 scraped off, unless they are wanted for immediate 

 examination . — Gosse's Aqtmrium . 



