140 



Prof. Karl Pearson. 



separation of the two groups which I suggested in 1887 is fully 

 justified by the recent work to which I have referred. By putting 

 the two groups on the same level of temperature, but on opposite sides 

 of the temperature curve, as in the evolutionary order forming part 

 of the meteoritic hypothesis, the differences are fully explained. 



It will be seen that this work carries us a step beyond that with 

 which I have recently been engaged in connection with the hotter 

 stars. 



General Conclusions. 



(1) The undoubted presence of dark carbon flutings in the solar 

 spectrum, including that near h, and of solar lines in the Piscian stars, 

 indicates that the Piscian stars are next in order of development to the 

 Arcturian stars. 



(2) The stars observed by Duner may be divided into seven species, 

 beginning with the hottest and ending with the coolest stars. 



(3) The reported presence of bright lines in the Piscian stars must 

 be received with caution, as similar evidence of bright lines might be 

 adduced in the case of other classes of stars in which the spectrum is 

 fully explained by dark lines alone. 



(4) The redness of the stars increases as we pass from the earlier to 

 the later species of the group. 



(5) The variability in this group is less marked than in the Anta- 

 rian stars, and may perhaps be accounted for by the revolution of 

 secondary bodies of the nature of comets round the stars themselves. 



(6) The place on the temperature curve assigned to these stars on 

 the meteoritic hypothesis is fully confirmed by the more detailed 

 inquiry, and the hypothesis is thereby strengthened. 



I am indebted to Mr. Fowler for assistance in the determination of 

 the species and the construction of the map ten years ago, and for 

 additional assistance in discussing the recent work. I have also to 

 express my thanks to Mr. Shackleton for a detailed examination of the 

 recent photographs. 



"Mathematical Contributions to the Theory of Evolution. — 

 On the Law of Eeversion." By Karl Pearson, F.RS. 

 (A New Year's Greeting to Francis Gal ton. — January 1, 1900.) 

 Received December 28, 1899,— Read January 25, 1900. 



(1) Introductory — In a memoir recently presented to the Royal 

 Society, I have endeavoured to emphasise the importance of distin- 



