398 Mr. E. Warren. The Variability of the Human 



XX. 41 Influence of Acids and Alkalis upon the Electrotonic 

 Currents of Medullated Nerve." By Augustus W. 

 Waller, M.D., F.R.S. 



XXI. " On the Distribution of Frequency (Variation and Correla- 

 tion) of the Barometric Height at diverse Stations." By 

 Karl Pearson, M.A., F.R.S., University College, London, 

 and Miss Alice Lee, Bedford College. 



XXII. " On the Openings in the Wall of the Body-cavity of Verte- 

 brates." By E. J. Bles. Communicated by Dr. Hans 

 Gadow, F.R.S. 



XXIII. " Electrification of Air, of Vapour of Water, and of other 

 Gases." By Lord Kelvin, G.C.V.O., F.R.S., Magnus 

 Maclean, D.Sc, F.R.S. E., and Alexander Galt, B-Sc, 

 F.R.S.E. 



ixxiv. " Note on recent Investigations on the Mechanical Equi- 

 valent of Heat." By E. H. Griffiths, M.A., F.R.S. 



The Society adjourned over the Long Vacation to Thursday, 

 November 18. 



" An Investigation on the Variability of the Human Skeleton 

 with especial Reference to the Naqada Race, discovered 

 by Professor Flinders Petrie in his Explorations in Egypt." 

 By Ernest Warren, B.Sc. Communicated by Professor 

 W. F. R. Weldon, F.R.S. Received April 2 —Read June 

 3, 1897. 



(Abstract.) 



Charles Darwin was the first to point out the great importance of 

 the study of the nature and causes of variation. Since his time, two 

 methods of investigation have been adopted ; in the one the obvious 

 and strongly pronounced variations are selected and the probability 

 of species having been derived from such " sports " is analysed and 

 discussed. According to the second method a population of a 

 species is taken, and the condition of the organs in each individual is 

 determined. It is believed that this latter statistical method will 

 lead to more accurate ideas as to the causes of variation and as to 

 the part which variation has played in the origin of species. 



As in all other scientific investigations, the course pursued by 

 statistical inquiry is, firstly, to record facts, and, secondly, to 

 generalise from the facts. The facts consist of the nature of the 



