IV 
CONTENTS. 
G 
PAGE 
Scottish National Antarctic Expedition. “ Scotia ” Collec- 
tions. Collembola from the South Orkney Islands. 
By George H. Carpenter, B.Sc., M.R.I.A., Professor 
of Zoology in the Royal College of Science, Dublin. 
(With Two Plates.) Communicated by William 
Evans, Esq., . . . . . .473 
( Issued separately January 14, 1907.) 
Statistical Studies in Immunity : The Theory of an 
Epidemic. By John Brownlee, M.D. Glas. Com- 
municated by Dr R. M. Buchanan, . . . 484 
{Issued separately January 14, 1907.) 
On a Simple Way of Obtaining the Half-Shade Eield in 
Polarimeters. By James Robert Milne, B.Sc., 
Carnegie Research Eellow, . . . .522 
{Issued separately January 14, 1907.) 
On an Exception to a Certain Theorem in Optics, with an 
Application to the Polarimeter. By James Robert 
Milne, B.Sc., Carnegie Research Eellow, . . 527 
{Issued separately January 14, 1907.) 
The Hessians of Certain Invariants of Binary Quantics. 
By Thomas Muir, LL.D., . . . .529 
{Issued separately January 16, 1907.) 
The Sum of the r-line Minors of the Square of a Deter- 
minant. By Thomas Muir, LL.D., . . 533 
{Issued separately January 16, 1907.) 
Obituary Notices, . . . 540 
Meetings of the Royal Society — Session 1905-1906, . 552 
Abstract of Accounts for Session 1905-1906, . . 561 
Index, . . .572 
