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XXXVII. — On the Freezing of the Egg of the Common Fowl. By John Davy, M.D., 

 F.R.S., Lond. and Ed., &c. (Communicated by Professor Maclagan.) 



(Read 2d May 1864.) 



In the Transactions of the Royal Society for 1778, Mr Hunter has given an 

 account of some experiments which he made on the freezing of the egg of the 

 common fowl, from the results of which he inferred, — " That the fresh egg has 

 the power of resisting heat, cold, and putrefaction, in a degree equal to many 

 of the more imperfect animals, .... and that it is more than probable, 

 this power arises from the same principle (a living principle) in both." 



Mr Paget, in the Transactions of the same Society, the volume for 1850, 

 has described how he repeated and added to these experiments of Hunter, but 

 whilst admitting their general accuracy, the conclusion he drew from them Avas 

 different, viz. — " That it is not by the power of a vital principle that eggs resist 

 the influence of cold," but is owing to the viscidity of the albumen, — to use his 

 own words, — " That the property which enables fresh albumen to descend below 

 32° Fahr. without freezing, is its peculiar tenacity or viscidity, by means of which 

 the water combined with it is held so steadily, that the agitation favourable or 

 even necessary to the freezing, at or near 32°, cannot take place."* 



The manner in which Mr Hunter and Mr Paget conducted their experiments 

 was similar. They both used strong freezing mixtures, and consequently there 

 was a rapid cooling of the eggs, which were subjected to the cooling process ; 

 thus, in the experiments of the latter, fresh eggs placed in temperatures varying 

 from zero to 10° Fahr. were frozen on an average in 26 minutes. In neither of 

 their experiments does it appear that the time of the exposure of the eggs was 

 prolonged much beyond half an hour. 



Considering the importance of the subject in its physiological bearings, and 

 reflecting on the circumstances under which their experiments were made, it 

 appeared desirable to repeat them with some modifications. This I have done. 

 The chief differences have been, that instead of an artificial mixture for cooling 

 the eggs, and a rapid refrigeration, the eggs, in the trials I have made, have been 

 exposed to the open air, and have been cooled more slowly. 



1. An egg, a fortnight old, was placed on grass and left out fully exposed to 



* Mr Paget assigns for the freezing-point of the egg a temperature of 32°, or between 31° and 

 32°, and supposes that it cannot fall below that, unless at perfect rest ; he says, — " That the egg 

 should be unmoved, and that its albumen should be not even so much disturbed as by the intro- 

 duction of the thermometer." My results, as will be seen, nowise accord with this. 



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