262 



NATURE 



\_Feb. I, 1872 



■little." Accordingly very little is said, and that little is 

 unimportant. Speaking of objects, Mr. Denning startles 

 us with the announcement that " Comets are not interest- 

 ing objects in a telescope" (we should like to hear upon 

 what experience he grounds this assertion) ; and he deals 

 with the hypothetical plant Vulcan by naively telling his 

 disciples that when a total eclipse of the sun " is in pro- 

 gress, the region of the heavens in the immediate vicinity 

 of the solar orb should be subjected to very careful 

 scrutiny." For such untutored gazers as are addressed in 

 the earlier pages the data in the later sections are insuffi- 

 cient. There are no times of rising and setting of the 

 moon and planets, no positions of Jupiter's sateUites at 

 times of eclipse, no information upon the points on the 

 moon's limb at which occulted stars will disappear and 

 reappear, no warning of the effects which change of geo- 

 graphical position will produce in some phenomena which 

 are computed for Greenwich only. Altogether the book 

 is a very weak production. J. C. 



Die Anuhiiden Australicns nach der Natur beschridtcn 

 tiiid abgebildet, von Dr. L. Koch. Erste Lieferung. 

 Pp. 56. Plates iv. (Nurnberg, 1871.) 

 Dr. L. Koch intends in this work to describe the spiders 

 of Austraha, not confining himself apparently to the 

 large insular tract that generally passes under this name, 

 but taking in also the Viti Islands, the Friendly, Pelew, 

 and other groups. In his Preface to this, the first portion 

 of his work, he says that though he has with much care 

 and industry for twenty years observed the Arachnida of 

 a little circuit of not more than from four to five hours 

 walk, yet every year there comes to light within this 

 small compass some new species that had up to then 

 remained concealed ; indeed it often happened that each 

 little journey increased the number of forms known in 

 the district. How true this observation is every investi- 

 gator will feel ; but knowing and feeling it, what courage 

 does it not require to set to work to write the history of 

 the spiders of a district which itself is not even yet half 

 explored ; and when the spiders are done, we are promised 

 another work on the Myriapods. Such courage deserves 

 to succeed, and we wish the enterprise every prosperity. 

 The work will be published at intervals of two months, 

 and be completed in two years ; each bi monthly part will 

 contain four plates and some five sheets of text. 



Following the families and genera as laid down by 

 Thorell in his " European Spiders," L. Koch commences 

 with the Epeiridit, and describes six new species of the 

 interesting genus Gasteyacantlia. Here, as in the other 

 genera, the new species are well figured by the author in 

 quarto plates. It is to be observed that some of the species 

 described are not to be met with, at least have not at 

 present been met with, in any part of Australia, but are 

 introduced into this work by the head and shoulders as 

 it were thus : — G. viohnta comes from New Guinea, and 

 G. hcpatica from Java. Two new genera, Tholia, with 

 three species, and ^«i'/.rzi! {ox Epcira liiomhoides, L.K., 

 are given. Ten new species of the genus Argiope are 

 described, and three new species of Cyrtarachne. The diag- 

 noses of the new genera are very properly given in Latin, 

 and the work may be regarded as quite indispensable to 

 all those engaged in the study of the spiders. W. 



LETTERS TO THE EDITOR 



[The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. No notice is taken of anonymous 

 communications. ] 



Change of Habits in Animals and Plants 

 Some weeks since I sent a few notes on Nestor notabilis,* show- 

 i.i^ a curious change in the history of this mountaineer. I now 

 beg I o add an extract from the Otago Daily Times, in contirma- 



• See Nature, vol, iv., pp. 489, 50S.; 



tion of this strange story of the progressive development of change 

 in the habits of the Kea, from the simple tastes of a honey-eater 

 to the sav.-igeness of a tearer of flesh : — 



" Some time ago we mentioned that Mr. Henry Campbell, of 

 Wanaka Station, had noticed that sheep on his run were fre- 

 quently attacked by birds. We are indebted to Mr. Cimpbell 

 for some further information on the subject. The birds in ques- 

 tion are of the kind called by shepherds " the mountain parrot," 

 and the scientific name of which is Nestor notabilis. The Maories 

 call it the Kea. The birds come in flocks, single out a sheep at 

 random, and each alighting on its back in turn, tears out the 

 wool and makes the sheep bleed, till the animal runs away from 

 the rest of the.sheep. The birds then pursue it, continue attack- 

 ing it, and force it to run about till it becomes stupid and 

 exhausted. If in that state it throws itself down, and lies as 

 much as possible on its back to keep the birds from picking the 

 part attacked, they then pick a fresh hole in its side, and the 

 sheep, when so set upon, in some instances dies. When the 

 sheep stops bleeding the birds appear to cease to attack it, though 

 Mr. Campbell is not very clear upon this point, and thinks they 

 attack it more for S|)ort than hunger. For three winters back 

 his sheep have been attacked in this way, and it was not till this 

 winter (though he previously suspected it) that he found the birds 

 were the olTenders. Where the birds so attack the sheep, the 

 elevation of the country is from 4,000 to 5,000 feet above the 

 sea level , and they only do so there i n winter time. On a station 

 owned by Mr. Campbell about thirty miles distant from the 

 other, and at tlie same altitude, in the same district, and where 

 the birds are plentiful, they do not attack the sheep in that way. 

 For tliose on whose stations they are an annoyance, it may be 

 mentioned that their numbers can be kept well thinned by shoot- 

 ing them. If one is wounded the rest gather round, and can 

 be shot in fives and sixes at a time." 



This note is interesting in the face of the destructive mfluence 

 commonly exerted by introduced upon native life. Here we have 

 an indigenous species making use of a recently imported aid for 

 subsistence, at the cost of a vast change in its natural habits. 



In the vegetable world we meet with a change in the habit of 

 a native species* which is somewhat analogous. 



Our Loranthus micranthns sometimes neglects its customary 

 supports, found often on such trees as Melicytns or Melieope (re- 

 presentatives of Violariea and Rutacece), for the more attractive 

 exotics, Cytisiis, Cra'tiegus, the plum, and the peach. Such 

 change in its habits this fragrant parasite acquires at the cost of 

 deserting the interlaced boughs of tangled gully for a more con- 

 spicuous position in the trim shrubbery or cultivated garden. At 

 this time I can see a most vigorous specimen of L. micranthns 

 growing on Cvtisns labiirnnm, covered with countless panicles of 

 perfuinedaden blossoms, on which our introduced bee is luxu- 

 riously regaling. Here we have the foreign bee gathering sweets 

 from native flowers growing on an exotic tree. 



In this neighbourhood the laburnum was first planted, 

 I believe, by myself, in 1859, and the bee introduced about the 

 same time. 



Ohinitahi, Oct. 7, 187 1 Thomas H. Potts 



A Case of Stationary Wave on a Moving Cord 

 It is well known to mathematicians that a stretched cord, 

 moving lengthwise with a velocity bearing a certain relation to 

 its tension and weight, will retain any curvature which may be 

 impressed upon it ; and consequently would pass through a 

 crooked tube without pressure agains'. its sides. That this may 



be the case, the velocity, Z', must equal . /t^-' ^ being the 



tension, and M the weight of the cord per unit of length. 



Passing from a stationary curve on a moving cord to one 

 moving along a fixed cord, it is easy to see that this velocity, V, 

 must be that of the transmission of a transverse vibration ; and 

 from this immediately follows the formula for the times of vibra- 

 tion of stretched strings. 



The case of the stationary wave, however, though simple in 

 theory, is rarely practically realised ; and I think a short notice 

 of a case in which it Is constantly produced may not be without 

 interest. 



In Captain Dennet's admirable invention for saving life from 



shipwrecks, a rocket is employed having a light line attached to 



it. This line is previously " laked down" on two rows of pins 



in a box ; and, the pins being withdrawn, it remains in a series 



* See Trans. New Zealand Institute, vol. iii., p. 190. 



