g Descendenz und Hybriden. 



Differentiation; he points out that Homotyposis was defined 

 as the degree of resemblance of like parts and is therefore a 

 correlation, but that Bateson speaks as if high Variation were 

 associated with low correlation and vice versa, and so shews 

 that he has not distinguished between them. He uses the term 

 Regression in an erroneous manner and even gives a new 

 meaning to the term H om o typ o sis duetoPearson himseli. 

 The author states that Bateson nowhere gives in his book on 

 „Materials for the study of Variation" concise definitions 

 which he follows throughout, for example there are three distinct 

 definitions of D isco nt i nuity and no one of them has been 

 used to test whether the cases he adduces are variations and 

 if so, discontinuous variations. 



The author states that he has investigated a great variety 

 of characters in a large number of populations including 

 hundreds of individuals and that he finds nothing like the 

 discontinuous Variation, which Bateson believes to be the basis 

 of evolution but on the contrary he does find evidence of pro- 

 gressive change in races by selection of continuous variations. 

 Heasserts that differentiation between like organs is distinguishable 

 bywell knowntests, andto Bateso n 's objection that, as differen- 

 tiation exists between pairs of brothers, the correlation between 

 differentiated like organs should have been included in the average 

 of the hornotypic tables, he replies that in the fraternal types 

 with which he was dealing such differentiation is insensible. 



The author shews that there is no foundation for Bateso n's 

 accusation that he has picked and chosen his cases, and new 

 material is cited to illustrate the definite clustering of homotypic 

 and fraternal correlations about the same mean values. 



The paper concludes by stating that differentiation can be 

 detected and allowed for by biometric methods, and that in the 

 near future mathematical knowledge will be a necessary part 

 of the biologist's equipment. Karl Pearson. 



Pearson. Karl, On the Systematic Fitting of Curves 

 to Observations and Measurements. (Biometrika. 

 Vol. I. Part III. p. 265—304 and Vol. II. Part 1. p. 1—24. 

 1902.) 



In this paper it is first shewn that most of the difficulty 

 of curve-fitting lies in the choice of a suitable curve. 



The author develops a systematic method of fitting curves 

 by „moments" and shews that if good quadrature formulae are 

 used this method is practicaily as good as the method of 

 least-squares, and is in many cases available where the latter 

 is impracticable and has in practice to be replaced by rough 

 empirical methods. 



Quadrature formulae due to Sheppard are given and shewn 

 to be more exact than the ordinary rules such as Simpson's 

 and N e w t o n ' s. 



