422 



NA TURE 



[April 2, 1874 



I have not seen any reference in the pages of Nature to the 

 experiments which have been carried on in German laboratories 

 in consequence of Prof. Huizinga's advocacy of Abiogenesis. 

 Dr. Paul Samuelson, experimenting with Huizinga's infusions 

 under tlie direction o( Prof Plliiger of Bonn, has obtained results 

 which negative the inferences of Prof. Huizinga. Dr. Samuel- 

 son's paper appeared in Plliiger's Archiv, during the past year, 

 and another experimenter (to whom I am unable to refer expli- 

 citly) has obtained equally definite results opposed to the specu- 

 lations of Bastian and Huizinga. 



Paris, Feb. 8 E. Ray Lankester 



Animal Locomotion 



I AM surprised to find that the Duke of Argyll prefers a 

 charge of plagiarism against me in 1S74 (N.\TURE, vol. ix. p. 

 3S1), said to have been committed by me in a lecture delivered 

 at the Royal Institution of Great Britain in 1S67. As his Grace 

 was present at the lecture in question, and lodged no complaint 

 in writing or otherwise, it appears to me that the charge, if not 

 unfounded and out of place, is at least out of time. As I am 

 not conscious of having perpetrated the plagiarism attributed to 

 me, I wish to apprise your readers that the lecture referred to 

 is published in extenso in the Proceedings of the Royal Institu- 

 tion of Great Britain, under date March 22, 1S67, and maybe 

 consuhed by all interested in the present discussion. That I had 

 no wish to appropriate from his Grace, but was, on the contrary, 

 desirous of giving him due credit for what he had done, will, I 

 hope, be evident from the following quotation : — " In order to 

 utilise the air as a means of transit, the body in motion, whether 

 it moves in virtue of the life ,it possesses or because of a force 

 superadded, must be heavier than it. If it were otherwise, if it 

 were rescued from the operation of gravity on the one hand, and 

 bereft of independent movement on the other, it must float about 

 uncontrolled and uncontrollable, as happens in the ordinary gas 

 balloon. The difference here insisted upon was, I have learned 

 since writing the above, likewise pointed out by his Grace the 

 Duke of Argyll, in his very able and eloquent article in Good 

 Words, entitled the 'Reign of Law.' . . . This article, lam 

 glad to find, has been reprinted in a separate form with numerous 

 illustrations, and should be read by all interested in the subject 

 of aeronautics." (" On the various Modes of Flight in Relation 

 to Aeronautics ; " Proceedings Royal Institution of Great Britain, 

 March 22, 1S67.) 



The only passage in the lecture bearing upon the point at issue 

 is opposed to his Grace's explanation of the direction of the down 

 stroke of the wing and in accordance with that originally given 

 by me and defended by Mr. Wallace in Nature, vol. ix. 

 p. 301. // cannot oonscquoiitly be regarded as a phgiarisj/i. 

 The Duke, it will be remembered, contends that the wing of 

 the bird strikes vertically dcai'uioards during the down stroke. I, 

 on the other hand, believe that the wing, during the down stroke, 

 invariably strikes do'tonwardsand/orwirds. In this Mr. Wallace 

 agrees with me. The passage in Cjuestion runs as follows : — 



"All wings obtain this leverage by presen ing oblique surfaces 

 to the air, the degree of obliquity gradually increasing in a direc- 

 tion from behind Jom'ards ami douiimnrds during extension, 

 when the sudden or eflective stroke is being given, and gradually 

 decreasing in an opposite direction during lluxion or when the 

 wing is being more slowly recovered preparatory to making a 

 second stroke. The effective stroke in insects, and this holds 

 true also of birds, is iheteforeAtWveKidoioinoards and forwards, 

 and not as the majority of writers believe, vertically, or even 

 slightly backwards. This arises from the curious circumstance 

 that birds, when flying, actually fall through ihe medium which 

 elevates them, their course berng indicated by the residlant of 

 two for'ces, viz., that of gravity pullirrg vertically downward.s, 

 and that of the wing actiiii; ata given angle in an np-coard dirce- 

 (ion. The wing of the bird acts after the manner of a boy's 

 kite, the only diflerence being that the kite is pnlled foiwards 

 upon the wind by the string and the hand, whereas in the bird 

 the wing is pushed Joi'^oards on the wind by the wtight of the 

 body ar d the lile lesiding m the pinion itself." [Op. cit, March 

 22, li!67.) The Duke, it i-i t.ue, compares the expanded motion- 

 less wings of a bird when sarling to a kite, v )i le I, as slated, 

 attribute a kite-actio:-i to the wings boih when ti.ey rise and fall. 

 The kite-actron in the one rnstance is, huwevtr, not to 

 be confounded with the kite-action in the other. That the 

 wings invariably strike daionwards and for^vards during the 

 down stroke, and upwards and forwards during the up stroke, 



and act as kites in either case, is a matter of observation, but still 

 more of experiment. I have again and again witnessed the 

 movement in the crow, cormorant, wild duck, and oiher birds, 

 and repeated experiments with natural and artificial wings serve 

 more and more to convince me that what I state is correct. But 

 for rhe downward and forward and upward and forward curves 

 made by the wings during the dowrr and up strikes, ])rogressive 

 flight would be impossible. The curves in question, when the 

 bird is advancing, unite to form wavid tracks on either side of the 

 body, thus representing the paths pursued by the vibrating wings 

 in every form and variety of flight. 



With regard to the poetical quotation introduced by me in my 

 lecture and alluded to by his Grace, I venture to think that few 

 will regard this as a case of plagiarism, 



Edinburgh, March 23 J. Belt, Pettigrew 



Electric Experiment 



The following striking experiment to show the rapidity of the 

 influence of sulphuric acid in removing the invisible film of 

 moisture that in ordinary circumstances adheres to the surface of 

 glass and deprives it of its quality as an electric insulator, was 

 recently shown to the Natural Philosophy class in the University 

 of Glasgow by Sir Willram Thomson, and as it may be inter- 

 esting to some of your readers, I send you an account of it. The 

 apparatus used were a gold-leaf electroscope, and one of the 

 ordinary table insulators long used in this University, of which 

 the following is a description. A A is a hollow cylinder of 

 brass, the lower ])art of v.'hich can be readily detached, replaced, 

 and fixed in position by a bayonet-joint. The cylinder is sup- 

 ported at the top by the glass rod S, which passes through a 

 circular opening in the bottom of the cylinder and is fixed to the 

 sole plate C. In the lower partis placed a circular canal of lead 

 containing a number of pieces of pumice stone //, which for 

 insulating purposes are moistened with a few drops of strong 

 sulphuric acid. On the previous evening the pumice// w'as 

 moistened with a few drops of water, the cylinder closed and 



left till morning. The experiment was then performed ihus 

 The gold leaves of the electroscope were connected with A A 

 by a fine wire and a charge communicated ; the gold leaves at 

 first repelled each other', but almost immediately collapsed. 

 This «as repeated once or twice, to show distinctly that there 

 was no insulation. 



The pumice containing water was then removed, and was 

 replaced by other piieces moistened with sulphuric acid (in both 

 cases the nroistening was so little that the pumice had the appear- 

 ance of being quite dry) and the vessel was ciosed. As the experi- 

 ment was made towards the end of the lecture and time was 

 pressing, a warm hand was placed on the side ol the insulator to 

 accelerate the drying proce-^s by creating connective currents in 

 the air. Wherher this hastened the effect or not sensibly it is 

 impossible to say, bur the insulation at once began to improve, 

 anil in less than five minutes tt was shown to be perfect by the 

 gold leaves remarninj diverj,ed to their lull extent. 



The University, Glasgow, March 21 D. M'Farlane 



