September 30, 1909] 



NA TURE 



409 



It is rather unusual to find that workers whose powers 

 of observation are equal take precisely the same view of 

 every member of a group of nearly allied forms. One, 

 from predisposition or accident, is influenced rather by the 

 characters whereby the forms differ ; another is more 

 impressed by those wherein they agree. In monographic 

 work especially the same worker may find himself alter- 

 nately more alive to the afiinilies and more struck by the 

 discrepancies among related forms. At one time lie feels 

 that his difficulties may be best solved by recognising all 

 these forms as distinct, at another he inclines to the view 

 that they may be but states of one protean species. Where 

 the capacity for detecting differences is naturally strong, 

 the disposition is towards segregation ; where there is a 

 keen eye for aflinities, the reverse. The facts in both cases 

 are the same ; their influence on minds in which the faculty 

 of observation, though equally developed, has a natural 

 bias in a particular direction may thus be different. 



This inherent variation in mental quality, of which the 

 observer may personally be unaware, and over which he 

 may have incomplete control, is not, however, so potent 

 a factor as a difference in mental ' attitude, usually the 

 result of training or tradition. The existence of two dis- 

 tinct attitudes on the part of authors ' towards their 

 " species " is common knowledge. In the absence of more 

 suitable terms we may speak of them as the " parental " 

 and the "judicial." To the parental worker his species 

 are children, whose appeals, even when ad misericordiarn, 

 are sympathetically received. To the judicial worker his 

 species are claimants, whose pretentions must be dis- 

 passionately weighed. The former treats the recognition 

 of a species as a privilege, the exercise of which reflects 

 honour. The latter views this task as a duty, the per- 

 formance of which involves responsibility. With amply 

 characterised forms the mental attitude is inconsequent, 

 but when critical forms are reviewed it is all-important. 

 Here the benefit of a doubt is the practical basis of final 

 decision. This benefit in the case of the parentally dis- 

 posed worker may lead to the recognition of a slenderly 

 endowed species ; in the case of the judiciallv inclined, to 

 the incorporation of an admittedly critical form in some 

 already described species, the conception of which may 

 thereby be unduly modified. 



These attitudes do not in practice divide descriptive 

 workers into two definite classes. Some writers display 

 one attitude at one period, the other at another period of 

 their career. Occasionally the two alternate more than 

 once in a writer's historx'. Cases are known in which one 

 attitude is consistently adopted towards species of one 

 .natural family, the other towards species of a different 

 family. 



When want of uniformitv in delimitation is due to the 

 varying effect of the same facts on different observers there 

 is no room for either praise or blame. Capacitv for 

 appreciating affinities is complementary to that for dis- 

 crimination. The fact that now one, now the other ten- 

 dency is more highly developed makes for general progress. 

 Workers in whom the two may be more evenlv balanced 

 can strike a mean between the discordant results of 

 colleagues more highly endowed than thev are in either 

 direction. But those who possess a capacity for com- 

 promise do not mistake this for righteousness ; they are 

 apt to wish themselves more gifted with the opposing 

 qualities of those whose work they assess. 



When cases in which want of uniformity in delimitation 

 due to difference in mental attitude on the part of in- 

 dependent workers are considered, we again find that praise 

 and blame are inappropriate. If both attitudes have defects 

 to be guarded against, both have merits that deserve 

 cultivation. The defects are patent and rarely overlooked ; 

 the careful systematist, more critical of his results than 

 anyone else can be, is alive to the risks which attend 

 stereotyped treatment, and on his guard against the 

 excesses to which this may lead. It is more often for- 

 gotten that both attitudes have their uses, and that each 

 should be exhibited at annropriate times. Here, however, 

 no middle wav is possible : the mean between the two 

 attitudes has the qualities of a base alloy. It is the atti- 

 t'lde of indifference, fatal to scientific progress, and pro- 

 ductive of results that are useless in technical research. 



The ideal nrransjempnt in monographic study is the 



NO. 2083, VOL. 81] 



collaboration of two workers, one highly endowed with the 

 discriminating, the other with the aggregating faculty. 

 But for the statement of their joint results both must 

 adopt the judicial attitude. ' On the other hand, in floristic 

 work, in isolated systematic contributions, and in all de- 

 scriptive work undertaken orr behalf of economic research, 

 the better because the more useful results are supplied by 

 workers in whom capacity and attitude combine to induce 

 the recognition rather than the reduction of easily 

 characterised forms. 



In the present state of our knowledge uniformit}' in the 

 delimitation of what are termed " species " is unattainable. 

 W'e are in no danger of forgetting this fact ; what we do 

 sometimes overlook is that, circumstanced as we are, such 

 uniformity is undesirable. The wish to be consistent is 

 laudable ; when it becomes a craving it blunts the sense 

 of proportion and may lead to verbal agreement being mis- 

 taken for actual uniformity. The thoughtful systematist, 

 when he considers this question without prepossession, 

 finds that forms which in one collocation need only be 

 accorded a subordinate position must, under other con- 

 ditions, receive separate recognition. 



The normal effect on specific limitation of the causes 

 that militate against uniformity is easily understood, and 

 the resulting discrepancies can be allowed for in statistical 

 statements. There are, however, cases where the capacity 

 for appreciating differential characters or points of agree- 

 ment is so highly developed as to obscure or even inhibit 

 the complementary capacity. The effects are then ultra- 

 normal ; nicety of discrimination exceeds the *' fine 

 cutting " allowable in floristic work ; aggregation exceeds 

 the limits useful in monography. No common measure 

 is applicable to the results, and the ordinary systematist, 

 who has definite and practical objects in view, expresses 

 his impatient disapproval in unmistakable terms. The 

 work of those addicted to one habit he characterises as 

 "hair-splitting"; that of those who adopt the other he 

 speaks of as "lumping." The industry displayed in 

 elaborating monographs which attribute a thousand species 

 to genera wherein the normal systematist can hardly find 

 a score must often be effort misplaced. The same remark 

 applies to the excessive aggregation that substitutes for a 

 series of quite intelligible forms an intricate hierarchy of 

 subspecies, varieties, subvarieties, and races. Orgies of 

 reduction are moreover open to an objection from which 

 debauches of differentiation are free. Discrimination can 

 onlv be effected as the result of study ; the finer the dis- 

 crimination, the closer this study must be. Reduction 

 offers fatal facilities for slovenly work, over which it 

 throws the cloak of an erudition that may be specious. 

 \\'hen dealing with excessive differentiation the normal 

 systematist is on solid ground ; when following extreme 

 reduction he mav become entangled in a morass. Yet 

 workers of both classes only exhibit the defects, for ordinary 

 purposes, of striking merits, and there are occasions when 

 the results that each obtains may be of value to science. 



Its mnemonic aualily renders taxonomic work practically 

 useful. Its application in economic resparch does the 

 same for specific determination. Economic workers are 

 chiefly interested in useful or harmful species ; to others 

 they would be indifferent were these not liable to be mis- 

 taken for such as are of direct interest. The identification 

 of economic species and their discrimination from neutral 

 allies is not always simple, because species that are useful 

 or noxious are often those least perfectly known. The 

 qualities that render them important frequently first attract 

 attention ; these may be associated with particular organs 

 or tissues, and samples of these parts alone may be ava'I- 

 able. Ordinarily, when material is incomplete, critical 

 examination has to be postponed. In economic work, 

 however, this may not be possible, and the systematist, 

 just ns in dealing with archaeological or fossil remains, 

 mav here have to make the most of samples and frag- 

 ments in lieu of specimens. Cultural help and anatomical 

 evidence sometimes lead to approximate conclusions ;^ often, 

 however, as with neutral species, definite determination 

 must await the communicafj'on by the field botanist of 

 adequate material. Even then a difficulty, comparable 

 with that frequently met with in archa;olog!ca! and 

 nala:obotanIcaI studv. may be encountered. As archaeo- 

 logical or fossil material may, owing to the conditions to 



