SECTION 22 OBSERVATION. 265 



"'When such a case as this occurs, and we have bare fresh land exposed, 

 it is of interest to watch the way it is colonised. The general law that 

 is followed is a series of changes, first from an entirely bare space to one 

 with a few species scattered at fairly regular wide intervals over the sur- 

 face, then by more species, the individuals growing closer together, but 

 each still with space to develop completely. At this stage there are 

 generally a very considerable number of species in proportion to the actual 

 number of individuals. Then the species really adapted to the soil and 

 the conditions begin to take a firm hold, and they grow more crowded 

 together and oust the others, till at the end, when the vegetation for the 

 spot is firmly established, there are great numbers of individuals which 

 completely cover the ground, but there are comparatively few species." 1 

 (Marie Stopes, Botany, 1912, pp. 55-57.) 



127. (h) Exhaustive or Full Observation. Examination 

 should be repeated from time to time, long after a case appears 

 established. A measure full and unmistakably running over 

 should be applied. There need to be incessant trials and varia- 

 tions in modes of procedure in order to ensure that nothing 

 material has escaped detection. 



When, however, we state that observation should be exhaus- 

 tive and full we mean that a liberal number of samples, derived 

 from the most varied sources, far and wide, has been accu- 

 rately and minutely examined. To ascertain, for instance, the 

 body's sensibility to touch or temperature, something like a 

 complete and minute examination of the surface of the body 

 may be desirable, and it is also indispensable that the examina- 

 tion should be repeated in part and wholly at different times, in 

 different places, and on sundry different bodies; but it would 

 be madness to settle down to an interminable series of exa- 

 minations. As Poincare (Science et methode, 1908, p. 8) well 

 says: "While the man of science discovers one fact, billions 

 upon billions take place in a cubic millimetre of his body." 

 Consequently, we signify by exhaustive examination, inspection 

 which ensures that we have satisfactorily examined a typical 

 sample of fact, with its more important variations, and not all 

 the facts as such. 2 



To furnish one example. Calculations purporting to give the 

 minimum annual cost of healthy and decent living for a standard 

 family of five in a certain locality and climate (allowing for 

 different seasons) should at least comprise food ; rent ; wearing 

 apparel (including repairs); lighting; fuel (for warming rooms 



1 The problems of commensality and symbiosis are of a kindred nature, 

 and are well worth the attention of the methodologist. See on the subject 

 J. Arthur Thomson, The Study of Animal Life, 1917. 



2 "One of the most striking things in Darwin's Autobiography is the re- 

 lative importance . . . which he assigns, in his analysis of his own educa- 

 tion, to the accumulation of facts and to the development of mental habits." 

 (Life and Letters of Charles Darwin, vol. 1, pp. 51-52.) Darwin "always 

 wished to learn as much as possible from an experiment, so that he did not 

 confine himself to observing the single point to which the experiment was 

 directed, and his power of seeing a number of things was wonderful." 

 (Frank Cramer, op. cit., pp. 29-30.) 



