320 



NATURE 



\Aug. 19, 1875 



fuel, nitric acid, and pyrites. The method has been in use at the 

 works of the "Lawei Clumical Manure Company" at Barking, 

 and the returns show that a saving of coal to the amount of | of 

 the quantity formerly burned has been effected— the total saving 

 in steam, nitric acid, and labour during three months, amounting 

 to five shillings per ton of acid of sp. gr. i-6 made from pyrites. 

 The patentee just points out that a saving of even one shilling 

 per ton means in this country an annual gain of 50,000/, 



The Rev. N. M. Ferrers, of Cambridge, author of "A 

 Treatise on Trilinear Co-ordinates," is preparing for the press a 

 work on Spherical Harmonics. The plan adopted in this work 

 will be first to discuss thoroughly the properties of the Zonal 

 Harmonic, for which various expressions will be given, and 

 general formulae investigated, by which any rational integral 

 function of one independent variable may be expressed in a series 

 of Zonal Harmonics. The properties of Tesseral and Sectorial 

 Harmonics will then be deduced from these. The expression of a 

 discontinuous function by means of Spherical Harmonics will be 

 discussed ; and various examples will be given of the use of 

 Spherical Harmonics in their applications to the theories of 

 attraction, and of electricity and magnetism. The book will be 

 published by Messrs. Macmillan and Co. 



"Pythagorean Triangles " is the title of a paper which was 

 read by W. Allen Whitworth, M.A., before the Literary and 

 Philosophical Society of Liverpool in February of the present 

 year. A Pythagorean triangle is a right-angled triangle having 

 all its sides commensurable. The most familiar instance is that 

 triangle whose sides are in the ratio of the numbers 3, 4, 5. 

 The author shows that one of the sides must be even (a multiple 

 of 4), one a multiple of 3, and that either a side or the hypo- 

 tenuse must be divisible by 5. Making use of a discovery of 

 Fermat's, he further shows that every prime number of the 

 form if N -^ I is the hypotenuse of such a triangle. The most 

 general results obtained are " the product of n prime hypo- 

 tenuses, all different, will be itself the hypotenuse of 2 "-1 

 Pythagorean triangles ; " this result is modified if m only 

 are different, to 2"*-^ Pythagorean triangles. With the 

 aid of these results he presents, in a tabulated form, 395 such 

 triangles, with hypotenuses less than 2,500. We may 

 mention that in Tebay's Mensuration a table of some 200 of 

 these triangles is given, but with no indication as to how they 

 are obtained. A great deal of information on the subject of 

 these triangles is given in vol. xx. of "Mathematics from the 

 Educational limes" at pp. 20, 54, 75, 76, 87, 97-100, to which 

 we refer such of our readers as may be interested in the matter. 



The West Riding Consolidated Naturalists' Society have pub- 

 lished the first number of a new monthly journal, the Naturalist. 

 A journal with a similar title was published in the same district 

 during the years 1865-6-7 ; we hope the present one will have a 

 much longer life. Its principal object is to afford a means of 

 communication among all Natural History Societies, either with- 

 in or outside the county of York. 



From the fourth Annual Report of the Chester Society of 

 Natural Science, we are glad to see that the Society is prosperous 

 and in good working order. The members now number 541, 

 and during the past year several excursions have been made, 

 several general meetings held for lectures, and the regular work 

 of the sections carried on. Altogether this Society seems in a 

 hopeful condition. The same Report contains a brief report of 

 the Wrexham Society of Natural Science, which seems to some 

 extent to be under the fostering care of its more prosperous 

 Chester sister. It seems to be, on the whole, doing well. 



Major Wood has sent us a reprint of two papers, with a 

 map, on the Aralo-Caspian region ; they originally appeared in 

 the Globe, the journal of the Geographical Society of Geneva. 

 Ramboz and Schuchardt, of Geneva, are the publishers. 



The additions to the Zoological Society's Gardens during the 

 past week include a Red Deer {Cervus elaphus), European, pre- 

 sented by Mr. ; Samuel Carter; a Malabar Squirrel [Sciurus 

 maximus) from S. India, presented by the Chevalier Blondin ; 

 two Purple Cow Birds {Molothrus purpurats) from Peru, pre- 

 sented by Prof W. Nation ; a Yellow-fronted Amazon {Chry- 

 sotis ochrocephala) from ^Guiana, presented by Mrs. Bolton ; a 

 Crested Peacock Pheasant {Folyplectron chinquis) from Malacca, 

 purchased ; three Hoffmann's Sloths [Cholopus hoff'manni) from 

 Panama ; three Spotted Cavies {Ccelogenys paca), a Coypu 

 {Myopotamus coypus) from S. America, an Argus Pheasant 

 {Argus giganteus) from Malacca, deposited. 



ON THE ACTION OF URARI ON THE 

 CENTRAL NERVOUS SYSTEM 



CINCE the introduction of urari twenty years back it has 

 ^ become more and more employed as an anaesthetic for phy- 

 siological experiments. Its effects on the peripheral portions of 

 the nervous system have been carefully studied, and are most 

 distinct and peculiar, so much so that they seem to have diverted 

 attention from its action on the central organs. Its effect, briefly, 

 when injected subcutaneously, is to produce a paralysis of the 

 motor nerves by attacking their ultimate branches. Dr. Foster, 

 at whose suggestion these experiments were undertaken, and to 

 whom I am indebted for much assistance, in the " Handbook 

 for the Physiological Laboratory " establishes the following pro- 

 positions : — I. "The effect of urari is to destroy or suspend the 

 irritability of nerves, but not of muscles." 2. " With moderate 

 doses of urari the small branches appear to be poisoned and to 

 have lost their irritability, while the trunks are still intact." He 

 also points out that " in order to bring these results out well, the 

 dose of poison must not be more than sufficient to poison the 

 motor nerves. Subsequent or stronger action of the poison 

 affects the central nervous system as well." Now it is perfectly 

 clear that the poison produces no appreciable effect on the sen- 

 sory nerves, and in consequence rash conclusions have been 

 drawn that it also has no effect on the sensorium, and is, in fact, 

 not an anaesthetic at all. 



The method of investigation employed was to take two frogs, 

 as nearly as possible alike in size and vigour, and to pass a liga- 

 ture round the whole abdomen (on Bernard's plan), taking care 

 to exclude from the ligature the sciatic plexus and to include the 

 blood-vessels. To one of the frogs a dose of urari was then 

 administered, and the two placed under similar conditions and 

 watched. The ligature in the poisoned frog of course prevented 

 the urari from gaining access to the hinder limbs, while it could 

 act fully on the nerve centres ; and the behaviour of this frog 

 could be compared with one which had merely undergone the 

 operation, and was clearly possessed of consciousness and voli- 

 tion. We will call the two frogs A and B, B being the one 

 which has the dose of urari. Now as soon as the poison took 

 effect, movements of respiration of course ceased, and the frog 

 lost control over its fore-limbs. On placing them side by side in 

 an unconstrained position, A constantly moved, executing large 

 and small movements with precision ; its actions seemed in no way 

 different from those of an uninjured frog. During this time the 

 frog B never moved, and although quite capable of using its 

 hind limbs, never did so ; at rare intervals (perhaps half an hour), 

 however, a movement was executed, but ot a very distinct kind, 

 a mere kick, such as a frog gives after the removal of its brain, 

 in virtue of pure reflex action ; now the innervation of the hind 

 limbs was quite intact ; the animal, if possessed of any wish to 

 move them, was quite able to do so, so far as its structural 

 arrangements were concerned. Indeed, the frog bore a striking 

 resemblance to one which had had its brain removed ; it behaved 

 in almost every respect in the same manner. 



If the two frogs be now laid on their face, a most convincing 

 experiment can now be tried. If the leg of A be forcibly ex- 

 tended and let go, it is drawn up ; it it be extended and held for 

 a short time, it is again drawn up. Now if the leg of B be ex- 

 tended and at once released, it is also drawn up ; but if it be held 

 for a second against the efforts of the animal to withdraw it, 

 these efforts cease and the limb retains its position for an almost 

 indefinite period. Now there can be only one explanation of the 

 behaviour of the frog B, namely, that the urari destroys con- 

 sciousness and volition at an early period ; that on extending 



