350 DR JOHN DAVY'S OBSERVATIONS ON INCUBATION. 



rest, a retardation might be effected of the changes unfavourable to life, and that 

 it might be indicated by some traces of vital development in the eggs. But the 

 results were all of the contrary kind ; in no one of the eggs were there any marks 

 of development. Two of them, No. 4 and No. 8 — the one which had sustained 

 the greatest loss during incubation, the other which had % sustained the least — 

 were opened under water. The air from No. 4, a little more than half a cubic 

 inch, was found to consist of 1 per cent, carbonic acid, 19 oxygen, 80 azote ; 

 whilst that of No. 8, somewhat less in quantity, consisted of 2*5 carbonic acid, 

 5 oxygen, and 925 azote. The contents of the two differed considerably. Those 

 of No. 4 were a mixture of yolk and white, forming a yellow fluid, of little 

 viscidity, of no unpleasant smell, of faint alkaline reaction, and giving off with 

 quicklime a slight smell of ammonia. The contents of No. 8 had an offensive 

 smell, approaching the putrid, a duller colour, a more distinct alkaline reaction, 

 and mixed with lime, a stronger ammoniacal odour. The contents of the other 

 eggs, with the exception of No. 7, were found to resemble very much No. 4. 

 They had no unpleasant smell, and, if anything, they were of a brighter yellow, 

 and of feebler alkaline reaction. No. 7 had undergone a greater change ; its con- 

 tents were of a greenish-mottled hue, nowise viscid, of unequal consistence, par- 

 tially curdled, of a very offensive putrid smell, strong alkaline reaction, and with 

 lime emitting a strong smell of ammonia. Under the microscope it was seen to 

 consist of very fine granules and of globules or cells, like those of a mucedo, in 

 which, it may be inferred, that the colouring matter existed. Now, as in all 

 these eggs, excepting one, putridity had not taken place, though the yolk and 

 white had become intimately mixed, and were exposed to a temperature favour- 

 able to the change, it seems pretty evident that a mere admixture of the two is 

 not adequate to excite the putrid fermentation, and that something else is essen- 

 tial. But what that something is, I cannot at present venture to conjecture. It 

 seems to me that the putrefaction of the egg, as regards its vera causa, is as yet 

 nearly as much unsolved as that of the coagulation of the blood, and, like it, may 

 perhaps be considered as belonging to the great mystery of life and death. 



