May 4, 1888.] 



SCIENTIFIC NEV/S. 



421 



Spider said to Feed on Zinc Sulphate. — Captain 

 T. P. Battersby, writing in the English Mechanic, quotes 

 with strong doubt the following statement from an old 

 work on chemistry : " It has been discovered by Mr. 

 Holt, the Secretary of the Cork Society, that spiders will 

 feed upon sulphate of zinc. One of these insects, kept in 

 a box for six months was found to have eaten nearly 

 4 ozs. of the salt." See Thomson's " Annals," vol. xii., 

 p. 454. If this is a fact, not merely our biology, but our 

 chemistry will stand in need of a serious revision. 

 But we may mention that spiders are • perfectly capable 

 of fasting for six months. 



Return of Birds of Passage. — Mr. H. Kerr, of the 

 Neivcasik Weekly Chronicle, mentions that the migrating 

 birds are this season putting in an early appearance on the 

 south coast. If this phenomenon is general, it refutes 

 the traditional notion that birds, whilst in their winter 

 retreats, have some mysterious knowledge of the kind of 

 weather prevailing in their summer haunts, and accelerate 

 or postpone their return accordingly. 



The Badger not Harmless. — Mr. J. D. Aysh {Field) 

 gives an instance of a badger shot in a fowl-house in the 

 very act of devouring a brood-hen which he had killed. 



Lions Bred in Captivity. — According to Mr. W. B. 

 Tegetmeir, 131 lion cubs have been produced in the 

 Dublin Zoological Gardens, of which no have been 

 reared, realising for the society ^^Zt^'^T- 



Intelligence of a Pelican. — According to a work 

 recently published by Madame Clemence Royer, a tame 

 pelican, which lived at St. Domingo, in a fisherman's 

 family, and received for its food the offal thrown 

 away in cleaning out the fish. It went every day to the 

 shore to meet the boats on their return. But as the 

 fisherman observed the Sunday's rest, the bird acquired 

 in time a precise notion of this weekly fast, and remained 

 sitting on its perch philosophically waiting for its repast 

 of the next day. Le Voltaire, quoting this incident, says, 

 " There exists no satisfactory definition of instinct, because 

 this expression represents nothing definite." 



Preservation of Otters. — Among naturalists of the 

 " aberrant " type, i.e., that is, those who approximate to 

 the sportsman, there is at present no little controversy 

 as to whether the otter should be extirpated as an enemy 

 to fish, or spared as a destroyer of some of the chief 

 enemies of the salmon and the trout ? The character of 

 the heron, too, is under discussion. 



How TO Seize Wasps and Bees without being 

 Stung. — Cosmos quotes from Science the assertion that if, 

 on seizing a wasp or a bee, we take the precaution not to 

 breathe, the capture may be effected with impunity and 

 without any protest on the part of the insect. A corre- 

 spondent of the latter paper states that, according to his 

 personal experience, this is quUe correct as far as wasps 

 are concerned. But in the case of hive-bees, wild bees, 

 and hornets the precaution is of no use. 



Voracity of the Bull-Frog in India. — According to 

 Eos [Field), this frog gobbles up young ducks and is very 

 greedy of small fishes. Hence he cannot, like his 

 European kindred, be protected as a harriiless and even 

 useful animal. 



FUNDAMENTAL EXPERIMENTS ON 

 THE NUTRITION OF PLANTS. 



WE propose to give plain instructions for the repe- 

 tition ot some of the cardinal experiments of 

 vegetable physiology, selecting those only which can be 

 successfully carried through with simple apparatus and 

 moderate experimental skill. Glass vessels of ordinary 

 forms, common chemical reagents, and a tolerable 

 balance will, as a rule, suffice. No unusual manipulative 

 skill is demanded, but merely that attention to minute 

 detail which all scientific experiment requires. The 

 reader who may desire fuller information on these and 

 other points of the physiology of plants is recommended 

 to refer to Sachs' or Vines' lectures. " Detmer's Pflan- 

 zenphysiologische Praktikum " is an excellent manual 

 for those who read German, and we have turned it to 

 account in preparing these instructions. 

 Experiment i. — Proof of the formation of organic 

 substance out of inorganic material by green plants. 

 Take dry beans or maize. Grind a few in a small 

 mortar to fine flour. Place some of the flour in a small 

 cup, weigh the cup and flour together with great care. 

 Dry at a temperature of 100° C. for half an hour in a 

 water-oven, and re-weigh, thus determining the pro- 

 portion of water in the seeds. Then select a few perfect 

 seeds, weigh exactly, place in distilled water until they 

 sprout, wash with more distilled water, and then rear by 

 water culture. 



Water culture is managed as follows : A tall cylindri- 

 cal glass vessel, holding from one litre to a litre and a 

 half (such a vessel would be about a foot high and 2 to 3 

 inches in diameter) is fitted with a sound cork about 

 I inch thick. A hole is cut in the centre of the cork, 

 large enough to take very easily the stem of the 

 plant under experiment ; the cork is then halved for 

 convenience in removing and replacing the plant. The 

 plant is to be held in place by a loose packing of cotton 

 wool. The roots are allowed to dip into the solution, 

 which fills the cylinder to within half an inch of the 

 cork. Experiments are usually carried on in a window 

 where sunlight enters freely. To prevent the growth 

 of microscopic vegetation in the nutritive fluid, the 

 cylinder is cased in black paper, but as this would cause 

 over-heating, if black outside, care is taken to blacken 

 the paper on one side only, and to turn the white side to 

 the light. 



A good nutritive fluid is made as follows : — 

 Calcium nitrate . . . . 1 gramme. 



Potassium chloride . . . . "25 ,, 



Magnesium sulphate . . . . "25 „ 



Potassium phosphate (KHjPO^) '25 „ 



Water i litre. 



Add to the mixture a few drops of dilute solution of 

 iron chloride. It is convenient to mix a large quantity, 

 and keep it in well-stoppered bottles in the dark. 



The soaked seeds must now be fixed, each in a separate 

 cylinder. The top of the roots must reach the water, 

 and the cotyledons within the seed-coats must be kept in 

 an atmosphere saturated with moisture, but not actually 

 immersed. A loose net made of threads knotted together 

 at one place is sometimes convenient for suspension of 

 the seed. As the fluid is absorbed, fill up with distilled 

 water. At intervals of two or three weeks, replace the 

 fluid by fresh solution. It is desirable to take out the 

 plants occasionally and lay their roots in distilled water 



