304 REPORT — 1903. 



native Rooks or of birds of passage, or both. There are a few records of 

 the return of Rooks to Scotland in the spring. 



9. In the autumn of some years apparently erratic movements west- 

 wards over the Atlantic have taken place. During these many of the 

 wanderers have been known to perish, while others have been observed 

 returning, in an exhausted condition, on the west coast of Ireland, and of 

 the Hebrides. 



The State of Solution of Proteids. — Report of the Committee, consistinrj 

 of Professor Halliburton^ (Chairman), Professor Waymouth 

 Keid (Secretarif), and Professor E. A. Schafer, appointed to 

 investiqate the state of Solution of Proteids. 



The test of solution employed in this research has been the production of 

 a lasting osmotic pressure upon a membrane impermeable to the proteid 

 when the pure solvent is exhibited on one side and the reputed solution on 

 the other side of the membrane. A positive result by direct manometric 

 observation is taken as indicating a condition of true solution, a negative 

 result as indicative of a state of fine suspension of the proteid. The 

 membrane used has been almost exclusively formalised gelatine supported 

 in the pores of peritoneal membrane, fixed on a perforated metal support, 

 and set in an osmometer in which continuous stirring for periods of six 

 to eighteen days was possible. 



The pressures were read daily with careful thermometric correction. 



Ovalbumin, serum-albumin, and various globulins have chiefly been 

 used for experiment, though work with other proteids is still in pi'ogress. 



Since the molecular weights of proteids is uncertain, the results have 

 been simply stated in the pressures in mm. of mercury for 1 per cent, 

 concentration of the proteid in reputed solution as determined by 

 analysis. 



As the source from which all proteids are drawn must, by the nature 

 of the case, be one heavily contaminated with other bodies, and as it is 

 well known that proteids absorb other bodies in solution very strongly, 

 attention has been largely directed to the purification of the material used 

 for experiment. In some cases crystallisation may assist, but it is believed 

 that thorough washing with salt solutions in which the crystallised or 

 precipitated proteid is insoluble, is the best means for removal of adherent 

 foreign substances. The purification of the material for experiment has 

 been the most laborious part of the research. 



The fact that solutions of similarly prepared samples of the same pro- 

 teid (say ovalbumin) obtained from different sources (different batches of 

 eggs) may give very different osmotic pressures per unit concentration of 

 proteid, suggested that the pressure read in such cases is not due to the 

 proteid in solution, but to some other body or bodies in true solution 

 and present in variable amount. 



If this is so, thorough washing of all such proteids, which in apparent 

 solution at first give an osmotic pressure, should finally yield a fluid hold- 

 ing proteid, but giving no osmotic pressure. 



This has been amply verified in the experiments, both in the case 

 of ovalbumin and serum-albumin, and osmotic-pressure-free proteid 

 * solutions' have been prepared without great difficulty, and the proteid 

 obtained dry by the vacuum pan for use in other experiments. 



