499 



SCIENTIFIC SIDE-LIGHTS 



Ocean 

 Opi>oites 



and in any direction. He has then the choice 

 of an infinite number of routes over the 

 whole earth. If such a man begins his wan- 

 derings in obedience to the impulse of his 

 own will, his own pleasure or interest 

 proceeding forwards, to the right or left, or 

 even backwards, with longer or shorter 

 pauses, and starting at any particular time 

 it is obvious that the route taken lies in 

 the man himself and is determined by his 

 own peculiar temperament. His judgment, 

 experience, and inclination will influence his 

 course at each turn of his journey, as new 

 circumstances arise. He will turn aside 

 from a mountain which he considers too 

 lofty to be climbed; he will incline to the 

 right if this direction appears to afford a 

 better passage over a swollen stream; he 

 will rest when he reaches a pleasant halt- 

 ing-place, and will hurry on when he knows 

 that enemies beset him. And in spite of the 

 perfectly free choice open to him, the course 

 he takes is in fact decided by both the place 

 and time of his starting and by circum- 

 stances which always occurring at every 

 part of the journey impel him one way or 

 the other; and if all the factors could be 

 ascertained in the minutest detail his course 

 could be predicted from the beginning. 

 WEISMANN Heredity, vol. i, p. 138. (Cl. P., 

 1891.) 



2455. ONTOGENESIS AND PHYLO- 

 GENESIS Embryological Development Not 

 Parallel with Geological. Ontogenesis is tha 

 embryonic development of the individual 

 animal, and is, of course, a short process, 

 depending on the production of a germ by 

 a parent animal or parent pair, and the 

 further growth of this germ in connection 

 more or less with the parent or with pro- 

 vision made by it.- This is, of course, a 

 fact open to observation and study, tho some 

 of its processes are mysterious and yet in- 

 volved in doubt and uncertainty. Phylo- 

 genesis is the supposed development of a 

 species in the course of geological time and 

 by the intervention of long series of species, 

 each in its time distinct and composed of 

 individuals each going regularly through 

 a genetic circle of its own. 



The latter is a process not open to ob- 

 servation within the time at our command 

 purely hypothetical, therefore, and of which 

 the possibility remains to be proved; while 

 the causes on which it must depend are nec- 

 essarily altogether different from those at 

 work in ontogenesis, and the conditions of 

 a long series of different kinds of animals, 

 each perfect in its kind, are equally dis- 

 similar from those of an animal passing 

 through the regular stages from infancy to 

 maturity. The similarity, in some impor- 

 tant respects, of ontogenesis to phylogenesis, 

 was inevitable, provided that animals were 

 to be of different grades of complexity, since 

 the development of the individual must nec- 

 essarily be from a more simple to a more 

 complex condition. On any hypothesis, the 



parallelism between embryological facts and 

 the history of animals in geological time 

 affords many interesting and important co- 

 incidences. Yet it is perfectly obvious that 

 the causes and the conditions of these two 

 successions cannot have been the same. 

 DAWSON Facts and Fancies in Modern Sci- 

 ence, lect. 1, p. 65. (A. B. P. S.) 



2456. OPINIONS ONAUTHORITY- 



Agreement of Specialists the Test. It is, 

 without doubt, the necessary condition of 

 mankind to receive most of their opinions 

 on the authority of those who have specially 

 studied the matters to which they relate. 

 The wisest can act on no other rule, on 

 subjects with which they are not themselves 

 thoroughly conversant; and the mass of 

 mankind have always done the like on all 

 the great subjects of thought and conduct, 

 acting with implicit confidence on opinions 

 of which they did not know, and were often 

 incapable of understanding the grounds, but 

 on which, as long as' their natural guides 

 were unanimous, they fully relied, growing 

 uncertain and skeptical only when these be- 

 came divided, and teachers who, as far as 

 they could judge, were equally competent, 

 professed contradictory opinions. Any doc- 

 trines which come recommended by the near- 

 ly universal verdict of instructed minds will 

 no doubt continue to be, as they have hither- 

 to been, accepted without misgiving by the 

 rest. MILL Positive Philosophy of Auguste 

 Comte, p. 90. (H. H. & Co., 1887.) 



2457. OPPORTUNITY IN LINE OF 

 NATURAL TENDENCY J. Time When Each 

 Acquirement Is Easy. In all pedagogy the 

 great thing is to strike the iron while hot, 

 and to seize the wave of the pupil's interest 

 in each successive subject before its ebb has 

 come, so that knowledge may be got and a 

 habit of skill acquired a headway of in- 

 terest, in short, secured, on which afterward 

 the individual may float. There is a happy 

 moment for fixing skill in drawing, for 

 making boys collectors in natural history, 

 and presently dissectors and botanists; then 

 for initiating them into the harmonies of 

 mechanics and the wonders of physical and 

 chemical law. Later, introspective psychol- 

 ogy and the metaphysical and religious mys- 

 teries take their turn; and, last of all, the 

 drama of human affairs and worldly wisdom 

 in the widest sense of the term. In each 

 of us a saturation-point is soon reached in 

 all these things; the impetus of our purely 

 intellectual zeal expires, and unless the topic 

 be one associated with some urgent personal 

 need that keeps our wits constantly whetted 

 about it, we settle into an equilibrium 

 and live on what we learned when our 

 interest was fresh and instinctive, without 

 adding to the store. JAMES Psychology, vol. 

 ii, ch. 24, p. 401. (H. H. & Co., 1899.) 



2458. OPPOSITES CONNECTED BY 

 INSENSIBLE GRADATIONS Circle, El- 

 lipse, Parabola, Hyperbola, Straight Line 



