Simple Mendelian Population Mating at Random. 37 
prove of considerable value in bacteriological investigations. Further experi- 
ments are now being made with other organisms which up to the present 
time have not been proved to be absolutely distinct. 
Numerous experiments were made on the resistance of these endotoxins to 
heat, and every result shows that they are thermostable even when exposed 
to a temperature of 100° C. for 30 minutes, and are still able to exert their 
specific action, as 1s shown by the following experiment :— 
No of No. of 
bacilli in non-phagocytic 
50 cells, cells. 
: A. Serum saline + leucocytes + B. Colt” ...cccceccecce neue scenes cases 233 0 
B. Serum Danysz extract + leucocytes + B. coli ....scccecceeee ees 59 15 
C. Serum coli extract + leucocytes + B. cold .......ce cece ccc eee eee 4, 46 
D. Serum Danysz extract* + leucocytes + B. COlt ..... ccc. cee cee ees 59 16 
HK. Serum coli extract* + leucocytes + B. colt .....ccce cece cee e ee 6 44 
* This extract was exposed to a temperature of 100° C. for 30 minutes. 
On the Determination of the Chief Correluitions between Col- 
laterals in the Case of a Simple Mendelian Populution 
_ Mating at Rundom. 7 
By EH. C. Snow, B.A., Biometric Laboratory, University College, London. 
(Communicated by Prof. Karl Pearson, F.R.S. Received June 3,—Read 
June 30, 1910.) 
(1) In a paper communicated to the Royal Society in April, 1909, 
Prof. Pearson obtained the gametic correlations between the offspring and 
the ancestry in each grade in a simple Mendelian population mating at 
random. By a “simple Mendelian population” for a viven character, he 
understood one which started with any definite ratio of dominant indi- 
viduals (AA) to recedents (aa). These mating at random give rise to a 
population which may be written in the form 
p* (AA) +2 pq (Aa) +9? (aa), 
and of which, without selection, the proportions of dominants, recedents, and 
hybrids are known to remain constant, with continued random mating, 
during successive generations. Prof. Pearson found that, both in the case 
of gametic and somatic characters, the ancestral correlations diminished in 
