309 



SCIENTIFIC SIDE-LIGHTS 



BBS," 



it is now ascertained, returns from the Ca- 

 naries or North Africa to the very spot on 

 which it built its little mud mansion the 

 previous summer, and according to the ob- 

 servations of the celebrated Jenner marked 

 birds were caught at their old nests every 

 year for three successive seasons. This fact 

 is so remarkable that, even after allowing 

 that the swallow tribe are gifted with ex- 

 traordinary powers of localization, and that 

 their summer homes are well denned, it is 

 something wonderful to remember that a 

 bird after seven months' absence can still 

 have treasured up in its memory, through 

 the varied fortunes and vicissitudes of two 

 long journeys, the recollection of the land- 

 marks necessary to guide it to and from its 

 summer home. BROWN Nature-Studies, p. 

 15. (Hum., 1888.) 



1504. HOMOGENEOUSNESS, AS- 

 SUMED, OF MICROSCOPIC CELLS Proper- 

 ties of Water Elude Microscope. Let me 

 say here that many of our physiological 

 observers appear to form a very inadequate 

 estimate of the distance which separates the 

 microscopic from the molecular limit, and 

 that, as a consequence, they sometimes em- 

 ploy a phraseology calculated to mislead. 

 When, for example, the contents of a cell 

 are described as perfectly homogeneous or 

 as absolutely structureless, because the mi- 

 croscope fails to discover any structure; 

 or when two structures are pronounced to 

 be without difference, because the micro- 

 scope can discover none, then I think the 

 microscope begins to play a mischievous 

 part. A little consideration will make it 

 plain that the microscope can have no voice 

 in the question of germ structure. Distilled 

 water is more perfectly homogeneous than 

 any possible organic germ. What is it that 

 causes the liquid to cease contracting at 

 39 F., and to expand until it freezes? 

 We have here a structural process of which 

 the microscope can take no note, nor is it 

 likely to do so by any conceivable extension 

 of its powers. TYNDALL Fragments of Sci- 

 ence, vol. ii, ch. 8, p. 125. (A., 1897.) 



1505. HOPE AND FAITH OPPOSE 



MATERIALISM For there are two great 

 enemies to materialism one rooted in the 

 affections, the other in the intellect. One is 

 the power of things hoped for a power 

 which never dies; the other is the evidence 

 of things not seen and this evidence 

 abounds in all we see. In reenforcing this 

 evidence, and in adding to it, science is 

 doing boundless work in the present day. 

 It is not the extent of our knowledge, but 

 rather the limits of it, that physical research 

 teaches us to see and feel the most. Of 

 course, in so far as its discoveries are really 

 true, its influence must be for good. To 

 doubt this were to doubt that all truth is 

 true, its influence must be for good. To 

 Reign of Law, ch. 2, p. 69. ( Burti ) 



1506. HOPE FOR HUMANITY'S FU- 

 TURE Past Gives Assurance. Thus, then, 



the most sanguine hopes for the future are 

 justified by the whole experience of the past. 

 It is surely unreasonable to suppose that a 

 process which has been going on for so many 

 thousand years should have now suddenly 

 ceased; and he must be blind indeed who 

 imagines that our civilization is unsus- 

 ceptible of improvement, or that we our- 

 selves are in the highest state attainable by 

 man. AVEBTJRY Prehistoric Times, ch. 16, 

 p. 576. (A., 1900.) 



1507. HOPEFULNESS OF SCIENCE 



Perplexities Yet Remaining. It must be 

 admitted that we do not at present appear 

 to have the means for framing a complete 

 and consistent theory of volcanic action, but 

 we may hopefully look forward to the time 

 when further observation and experiment 

 shall have removed many of the existing 

 difficulties which beset the question, and 

 when by the light of such future researches 

 untenable hypotheses shall be eliminated 

 and the just ones improved and established. 

 JUDD Volcanoes, ch. 12, p. 360. (A., 

 1899.) 



1508. HORIZON, MENTAL, EXTEND- 

 ED Individual Experience Not the Limit 

 History, Etymology, Mythology, and Re- 

 ligion Tributary to Psychology. But how is 

 it possible to extend our experience of sen- 

 sations, feelings, and thoughts? Did not 

 mankind feel and think thousands of years 

 ago as it feels and thinks to-day? It does, 

 indeed, seem as tho our observation of 

 what goes on in the mind could never extend 

 beyond the circle to which our own con- 

 sciousness confines it. But appearances are 

 deceptive. Long ago the step was taken 

 which raised the science of psychology above 

 the level of this its first beginning, and ex- 

 tended its horizon almost indefinitely. His- 

 tory, dealing with the experience of all 

 times, has furnished us with a picture in 

 the large of the character, the impulses, and 

 the passions of mankind. More especially 

 is it the study of language and linguistic 

 development, of mythology, and the history 

 of religion and custom, which has ap- 



Eroached more and more closely, as histor- 

 ial knowledge has increased, to the stand- 

 point of psychological inquiry. WUNDT 

 Psychology, lect. 1, p. 10. (Son. & Co., 

 1896.) 



1509. HORSE A MIGHTY ENGINE 



Adaptation to Needs of Man. The teeth of 

 a horse are not less peculiar than its limbs. 

 The living engine, like all others, must be 

 well stoked if it is to do its work; and the 

 horse, if it is to make good its wear and 

 tear, and to exert the enormous amount of 

 force required for its propulsion, must be 

 well and rapidly fed. To this end, good cut- 

 ting instruments and powerful and lasting 

 crushers are needful. Accordingly, the 

 twelve cutting teeth of a horse are close-set 

 and concentrated in the fore part of its 

 mouth, like so many adzes or chisels. The 

 grinders or molars are large, and have an 



