May, 1904.] 



KNOWLEDGE c<t SCIENTIFIC NEWS. 



89 



both "canals" and "oa<:es," as sliown by Mr. Lowell, is 

 not conriniied by the best obser\ers. In tiie last number 

 of " Kniiwi.epgk " Mr. Denning writes (p. 67) : " There 

 are really many distinctions in the canal -like markings ; 

 some of them are (juite broad and ditTused shadings, 

 while others are narrow, delicate lines." The Rev. 

 T. E. Phillips has recently insisted strongly (" Monthly 

 Notices," \'ol. LXI\'., p. 40) on the same fact, and 1 

 could increase the testimony indefinitely. There can be 

 no doubt that the best observers not merely agree in 

 stating that the "canals" differvery widely in their charac- 

 teristics, but they also agree closely in the characteristics 

 they assign to special "canals." With regard to I-owell's 

 observations 1 can, of course, speak only with reference 

 to those which he has published, but speaking with re- 

 ference to these there can be no doubt that he fails to 

 e-xhibit that wide variation in character between cer- 

 tain "canals" upon which these and other leading 

 observers are fully agreed. This seems to me clear 

 proof (so far as his published drawings go) not of superior 

 conditions and skill -on Mr. Lowell's part, but of 

 a most marked inferiority in one respect or the 

 other. Whether it be the location of his observatory 

 that is at fault, or the definition of his telescope, or his 

 own personal skill in observation, or most probable of all, 

 in delineation, the fact remains that- -despite the multi- 

 plicity of his observations and the perseverance, which 

 cannot be too highly praised and too fully recognised, 

 with which he has observed Mars in season and out of 

 season — he has failed to record difTerences apparent to a 

 consensus of other first-rate observers. Especially he 

 has failed to recognise what Denning and Schiaparelli 

 had recognised as early as 1884, that many of the 

 " canals " were very far from being straight lines of 

 uniform breadth and darkness, but showed evident 

 gradations in tone, and irregularities occasioning breaks 

 and condensations here and there. Of all the thousands 

 of drawings of Mars which I have examined, those that 

 most perfectly corresponded to Mr. Lowell's were the 

 work of a young novice and were made in by no means 

 an ideal station, using a small home-made telescope. 



It is made an argument in favour of the actuality of the 

 " canals " that they have been seen with such distinct- 

 ness, or with such frequency. The argument is based 

 upon a very complete ignorance of the appearance of the 

 fictitious "canals" observed in the experiments made by 

 Mr. Evans and myself. I have myself been completely 

 taken in by a little drawing on which the Syrtis Major 

 and Sinus Sabseus were shown. As I looked at it by 

 far the most insistent feature was a straight, narrow, 

 intensely black line corresponding to the Phison. Yet 

 that astonishingly vivid impression was really due to the 

 integration of two or three feeble lines, irregular, broken, 

 and serpentine curves, and half a dozen utterly invisible 

 dots. If I had looked at that drawing a thousand times, 

 or if a thousand other observers had examined it under 

 the same conditions as to distance, they could only have 

 seen what I saw — a dark, straight line, as sharp as if cut 

 by a graving tool. 



The change in the distinctness of the "canals," con- 

 sequent on the progress of the Martian seasons, was no 

 discovery of Lowell's; the fact was realised by Schiapar- 

 elli very early in his observations. But so far from 

 rendering it more probable that the "canals" indicate 

 artificial water-ways, it affords a most serious argument 

 against their having that character. For water cannot 

 flow uphill, yet the water from the melting polar snow, 

 according to Lowell, must flow upwards to reach the 

 equator. If, with Lowell, we consider the dark markings 

 on Mars to be vegetation rather than water, they would 



change in appearance with the seasons whether they were 

 of natural origin and irregular shape, or were artificial and 

 symmetrical; and Mr. Lowell's S500 ohser\ati()ns do not 

 increase the probability of his theory more than 85 or Hh 

 would do. .\ " canal " or an " oasis," if seen only as a 

 straight line or a circular dot, that is lo say, if seen only 

 in the simplest possible form, affords no proof that the 

 precise form under which it appears has any actuality. 

 It is only when the object begins to show detail that we 

 are sure that we are beginning to sec it as it is. And one 

 of the most convincing testimonies that Mr. ICvans and 

 myself have been following the right line has been shown 

 by the attitude which the most experienced observers of 

 Mars have adopted towards our intjuiry. They have 

 claimed, as Mr. Denning did in last month's " Know- 

 i.EDc.E," that certain "canals" are undoubtedly real, for 

 they have been resolved or partially resolved into minuter 

 details, being "composed of small, irregular condensa- 

 tions." Others they have admitted may be "canals" 

 only in appearance, being actually either " the edges of 

 half-tone districts or the summation of very minute 

 details." In both the claim and the admission they are 

 in perfect accord with the position held by Mr. Evans 

 and myself. On the other hand, Antoniadi, Bariiard, 

 Denning, Molesworth, Stanley Williams, have all held 

 themselves aloof from the bizarre delineations and yet 

 more bizarre theories which Lowell has promulgated. 

 Most striking of all, Mr. W. H. Pickering, who preceded 

 Mr. Lowell in his argument that the water supply in 

 Mars is restricted, and in the recognition of the system of 

 " oases," who further has had the opportunity of observ- 

 ing with Mr. Lowell's telescope and in the climate of 

 Arizona, has not only frankly accepted our position, but 

 has supported it by direct photographic proof. Mars, 

 unfortunately, does not lend itself to photography, but 

 the Moon does; and Mr. Pickering has found confirma- 

 tion of our experiments as to the building up of straight- 

 line systems from imperfectly seen details by comparing 

 his drawings of certain lunar formations with actual 

 photographs. 



Stimulus and Sensation 



By J. Reynolds Green, Sc.D., F.R.S. 



If we contemplate the enormous variety of form and 

 structure which we find to exist among plants, and en- 

 deavour to study the reasons which we can readily trace 

 for the diversity in these respects, the conviction is 

 forced upon us that the story which is hidden there is 

 one of stress and struggle, the result being a correspon- 

 dence between the plant and its environment, so that 

 the former can take advantage of all that is offered to 

 it by the latter, and can resist successfully such dele- 

 terious influences as are inevitable from its situation. 

 Hence different environment entails different structure. 

 Moreover, as the en\ironment is continually changing 

 in some respect or other, the organism is continually 

 involved in the struggle to adjust itself to the alterations 

 thus besetting it. in the absence of power to maintain 

 satisfactory relations, the plant becomes unhealthy, and 

 after a time it perishes. Health, indeed, is but the ex- 

 pression of a satisfactory equilibrium gained and main- 

 tained between the plant and its surroundings. 



