128 Scientific Proceedings, Royal Dublin Society. 



by 0'035° C. The range of variation iu A for the egg of Grallus is 0-053° C. ; 

 wliile in Anas, differences amounting to 086° 0. were found. These fluctu- 

 ations are considerably greater than those found in tlie blood ; and the value 

 of A is in every case much less than for the blood. The egg-white is a 

 secretion ; and as secretions often differ widely from the blood in concentration, 

 there is nothing surprising in tliis. It is, however, remarkable that the ovum 

 proper, which was in equilibrium with the blood and body-fluids hefore 

 becoming detaclied, is found in a nutrient medium of mucli smaller osmotic 

 pressure. 



The cause of this reduction in osmotic pressure lias now to be sought. Is 

 it due to a diminution iu the inorganic salts, of which sodium chloride is 

 by far the most important, and the others may be assumed to vary witli it ; 

 or is it due to a decrease in the organic crystalloids present ? To decide this 

 question an analysis was made of the chlorine in the white of duck-eggs and 

 in the plasma of duck-blood, from which the red corpuscles had been separated 

 by a centrifuge. A few determinations of the chlorine in sera of other 

 birds were also made ; but these were not quite free from red corpuscles. Tlie 

 analysis was carried out by drying and igniting the egg or serum in a covered 

 crucible, and then dissolving the ash in dilute nitric acid and titrating the^ 

 chlorides by Volhard's method. As the quantities of chlorine found 

 amounted only to from 0-03 - 0'02 grm., the accuracy attained is not very great. 



Mean, 



As NaCl, 0-473 percent. As NaCl, 0-148 per cent. 



These results make it clear that there is a great loss of chlorides in the 



Qgg, the amount present being only about one-third of that in the blood 



plasma. Consider now the role played by the chlorides in lowering the 



freezing-point. The amount of chloride iu the serum, calculated as the 



