568 SCIENCE PROGRESS. 



ever it is possible the numerical proportions which the type, 

 the variety, and the intermediates bear to each other should 

 be determined carefully by statistical seriation. This must 

 be done in suitable cases by measurement, and in other 

 cases by the constitution of a series of grades and counting" 

 the specimens belonging to each grade. But even where 

 by the intrinsic circumstances of the case or by the condi- 

 tions under which the collecting or observations have to be 

 conducted, numerical estimations cannot be made, it is cer- 

 tain that most valuable material would be provided merely 

 by answers to the first two questions, with a careful state- 

 ment of impression as to the third point. These answers 

 would not merely show roughly whether the case was likely 

 to repay further and special investigation, but they would 

 provide that general outline of the properties of species in 

 regard to variation which all the labours of the systematists 

 have failed to provide, though it has become an urgent 

 necessity to progress. The systematists have given us a 

 catalogue of the material, treating it from the cataloguer's 

 standpoint, but in the light of the study of variation we are 

 still at the first recension. 



In a subsequent part the application of these methods to 

 the special problems presented by local races will be con- 

 sidered. 



REFERENCES. 



(i) Barrett. Eni. Mo. Mag., 1895, xxxi., p. 201. 



(2) Bateson. Materials for the Study of Variatio7i, 1894. 



(3) Chappell. Ent., 1886, p. 253. 



(4) Coubeaux, C. R. Soc. ent. Belg., 1886, p. cxciii. 



(5) De Selys Longchamps. Ent., 1895, p. 7. 



(6) MiLLIERE. leonographie, ii., p. 228, PI. 75. 



(7) South. Ent., 1893, p. 257, 



(8) StandfuSS, Handb. der faldark Gross-Schmet, 2nd ed., 1896. 



(9) Steinert. Iris, deut. ent. Ges., Lep. Hefte, 1892, p. 424. 



W. Bateson. 

 {To be continued.^ 



