io6 



NA TURE 



[June 4, 1908 



solution upon the lines indicated, there is no reason 

 beyond that of expense why vision should not be 

 electrically extended over long distances. The only 

 method which can be regarded as feasible (unless, in- 

 deed, M. Armengaud has made a revolutionary dis- 

 covery) is that suggested by the structure of the eye 

 itself'; the essential condition is that every unit area 

 of the transmitter screen should be in permanent and 

 independent connection with the corresponding unit 

 of the receiving screen. This idea would naturally 

 present itself to anyone approaching the subject for the 

 first time, but would probably be rejected in favour 

 of something apparently more simple. ^ Such an 

 apparatus could, however, be constructed without an} 

 serious complexity apart from that arising from th( 

 mere multiplication of its components. I have made 

 a rough estimate of the cost, assuming the stations 

 to be 100 miles apart, the received picture to be 2 

 inches square, and the length of a unit to be 1/150 

 inch. Of each of the elementary working parts- 

 selenium cells, luminosity-controlling devices,^ pro- 

 jection lenses for the receiver, and conducting v.'ires — 

 there would be 90,000. The selenium cells would be 

 fixed on a surface about 8 feet square, upon which the 

 picture would be projected by an achromatic lens (not 

 necessarily of high quality) of 3 feet aperture. 

 The receiving apparatus would occupy a space of 

 about 4000 cubic feet, and the cable connecting the 

 stations would have a diameter of 8 or 10 inches. 

 The thing could probably be done for 1,250,000/., but 

 not for much less. By an application of the three- 

 colour principle it would be possible to present the 

 picture in natural colours, like that shown' upon the 

 focussing screen of a camera. The cost would in that 

 ease be multiplied by three. 



Shelford Bidwell. 



ARISTOTLE AND NATURAL SELECTION. 



A PASSAGE of Aristotle's " Physics," in which he 

 alludes to the theory of natural selection, has 

 been frequently quoted and almost as frequently mis- 

 interpreted. It may therefore be worth while to de- 

 vote a short space to a careful consideration of its 

 import. 



The passage in question is in the " Physica Auscul- 

 tatio," ii., S, §§ 1-6. In it Aristotle begins by assert- 

 ing the existence in nature of final causes (evexti rov 

 alriai). He next considers objections that may be 

 brought against this view, as, for example, that rain 

 falls simply in obedience to natural law (t^ dwiyxr;?) 

 and not for the sake either of making the corn grow 

 or of spoiling it when cut. So, too, the supposed ob- 

 jector proceeds, with the parts or organs of animals; 

 what is to prevent us from saying that the teeth 

 originate in their various forms of incisors and molars 

 simply by the operation of natural law ? That they 

 are serviceable respectively for cutting and grinding 

 is not purposeful, but coincidental {ov tovtov epfxa 

 yfveaSai, a\\a trviinea-e'iv). The existence of these ap- 

 parent adaptations, the objector adds, can be accounted 

 for by the fact that, as Empedocles has pointed out, 

 those organisms that are unfitted for their conditions 

 do not survive, but perish. 



It will be seen from the foregoing that Aristotle 

 does not advance the theory of natural selection as 

 part of his own explanation of adaptation in nature, 

 but as a principle that might be used to reinforce an 

 alternative view. 



We may now turn (o his answer. The objection, 

 he replies, will not hold, because things that arise 

 naturally (<^i»'a-€i) always, or nearly always, come about 

 thus; i.e., like the teeth, already adapted and fit to 

 survive; while beings such as the unadapted monsters 



NO. 2014, VOL. 78] 



imagined bv Empedocles originate, if at all, by chance 

 or spontaneously (diro tvxV^ ""' ''°"' niVo/jnroi/), and are, 

 Aristotle would say, outside the ordinarily observect 

 course of nature. It cannot be alleged, he goes on 

 to point out, that such phenomena as rain and warm 

 weather are altogether dependent on chance or coinci- 

 dence {ano t;^;(t;s ovS' aTvo (rvfinraiiaTos). Warm weather 

 is the rule in the dog-days, and rain in winter. 

 Everyone admits that things of this kind are in accord- 

 ance with the ordinary course of nature ; and if they 

 occur in this regular way neither of themselves (like 

 monsters) nor by mere coincidence (lilie unseasonable 

 rain) it remains that they must exist for some pur- 

 pose {ravT ev€Kd rov av e'irj). It must then be con- 

 cluded that final causes exist in reference to natural 

 products (i'aTiv tipa tu iViKa rov tv toIs <fiv(j€t yiyvo^tvois koI 

 ovcnv). 



Whatever may be thought of Aristotle's argument, 

 it is clear that his general object throughout this 

 passage is to defend his doctrine of final causes (it is 

 to be observed that he does not say that final causes 

 are of universal operation). He is unable to fall in 

 with the view of natural selection as propounded by 

 Empedocles, because, as it appears to him, adaptations 

 are produced read\-made ; the non-adapted is not 

 merely eliminated, but seldom comes into existence 

 at all. He seems, however, to admit that for those 

 who believe (as he does not) in a purely fortuitous 

 origin of natural objects, the hypothesis of natural 

 selection affords a feasible explanation of adapted 

 structures. 



The erroneous views that have been taken of this 

 passage by various writers have been due, I think, to 

 the general failure to recognise that the whole of 

 sections 2, 3 and 4 are devoted to Aristotle's statement 

 of a possible objection to his own opinion. Thus 

 Gomperz (" Griechische Denker," xiv., pp. 103, 104; 

 Leipzig, 1908), although he clearly states Aristotle's 

 position with regard to the Empedoclean monsters, 

 nevertheless quotes the sentence about the rain and 

 the growing corn as if it gave Aristotle's own ex- 

 planation instead of the plea of an opponent. Osborn 

 (" From the Greeks to Darwin ") falls into the same 

 error ; the author of a pamphlet (Ai tu>v Lamarck koX 

 Darwin Qewplai irapa tw ' ApiiTTOT(KeC), lately published 

 at Athens, has similarly missed the point; nor has 

 Darwin himself escaped the like misapprehension, for 

 which probably the translator on whom he relied was 

 responsible (" Origin of Species," note to " Histor- 

 ical Sketch " in the later editions). On the other 

 hand, the general drift of the passage was rightly 

 appreciated by G. H. Lewes, though the confusion of 

 ideas with which he taxes it belonged, perhaps, 

 rather to his own mind than to that of Aristotle. 



F. A. DiXEY. 



NOTES. 

 We notice with deep regret that Sir John Evans, 

 K.C.B., F.R.S., died at his residence, Britwell, Berk- 

 hampsted, on Sunday, May 31, in his eighty-fifth year. 



Sir George Darwin, K.C.B., F.R.S., and Prof. E. B. 

 Tylor, F.R.S., have been elected corresponding members 

 of the Vienna Academy of Sciences. 



The twenty-fourth Congress of the Royal Sanitary 

 Institute will be held at Cardiff on July 13-1S, under the 

 presidency of the Earl of Plymouth. In addition to 

 sectional meetings, there will be a number of conferences 

 on various aspects of sanitary science, among the subjects 

 being spring cleaning and its sanitary significance, and the 

 sorting and grouping of school children for educational 

 purposes. 



