Septembee 28, 1900.] 



SCIENCE. 



481 



of a concept, neither can it become ade- 

 quately known to us through the medium, 

 of description. Botany without designation 

 of types is like geography without position. 



In biology a species is a coherent or continu- 

 ous group of organisms. In such a group the 

 individual organisms have a common origin 

 and may be arranged in connected series of 

 imperceptible gradations with reference to 

 any one character, except in cases of sexual 

 differentiation and alternation of genera- 

 tions, where the coherence of specific groups 

 is maintained by facts of life-history. A 

 species is not constituted by any antecedent 

 determination of the amount of difference 

 it must present ; it subsists in virtue of the 

 fact that it has diverged and become dis- 

 connected in nature from other groups of 

 organisms, however similar these may be. 

 For nomenclatorial purposes a species is a group 

 of individuals which has been designated by a 

 scientific (preferably a Latin adjective') name, 

 the first individual to xohich the name ivas ap- 

 plied constituting the type of the species. The 

 importance of preserving type specimens 

 with special care is now recognized through- 

 out the scientific world, and where specific 

 types are lacking, naturalists are endeavor- 

 ing to supply their place by specimens col- 

 lected in the original localities. This, may 

 be taken as a general admission of the 

 obvious fact that purely descriptive methods 

 are generally insufiicient for scientific ac- 

 curacy and need to be supplemented by 

 actual specimens if correct identifications 

 are to be permanently assured. 



For purposes of reference and citation specific 

 names which appeared previous to the ' Species 

 Plantarum ' of Linnaeus are not regarded in 

 botanical nomenclature. In reality Linnseus 

 revived rather than originated the binomial 

 system of nomenclature, but his works em- 

 body the results of the first extensive and 

 fairly consistent attempt at the scientific 

 application of the nomenclatorial practice 

 now universally followed. 



The method of types applied to genera 

 involves a similar readjustment of views. 

 Under the analytic method of concepts a 

 genus has been defined as a sub-division of 

 a family, but the method of types is 

 synthetic and places the emphasis on the 

 connection with nature by building the 

 genus up from below. 



A genus of organisms is a species without close 

 affinities, or a group of mutually related species. 

 Here again the natural arrangement must 

 have reference to the gaps in nature rather 

 than to the logical balance of formal char- 

 acters. 



A generic name is established in taxonomy 

 xvhen it has been applied to a recognizable species. 

 Unless the discoverer of the genus desig- 

 nates a type species in the same publication 

 in which he bestows the name, the first 

 species referred to the genus should serve 

 as its nomenclatorial type. 



The generic taxonomy of plants may be treated 

 as beginning ivith Tournefort's ' Institxdiones ' 

 (1700). 



O. F. Cook. 



Washington, D. C. 



SCIENTIFIC BOOKS. 

 Memoirs presented to the Cambridge Philosoph- 

 ical Society on the occasion of the jubilee of 

 Sir Geoege Gabriel Stokes, Bart., Hon. 

 LL.D., Hon. Sc.D., Lucasian Professor. Cam- 

 bridge, at the University Press, 1900 ; New 

 York, The Macmillan Co. 4to. Pp. xxviii 

 + 447, with 25 plates. Price, $6.50. 

 The celebration of the fiftieth anniversary 

 of the Lucasian professorship of Sir George 

 Gabriel Stokes at the University of Cambridge, 

 on June 1 and 2, 1899, brought together a 

 large number of distinguished naturalists, if 

 one may use this convenient term to include 

 astronomers, chemists, geodesists, geologists 

 mathematicians, physicians, physicists and 

 zoologists. It was one of those occasions 

 which illustrate the essential unity of science 

 by a spontaneous tribute of homage to an emi- 

 ■ neut specialist from workers in widely diver- 

 gent fields. During the week following the 



