SECT. I] PHYSICO-CHEMICAL SYSTEM 367 



tein. The result came out to 10-4 x io~^. If this work were repeated 

 for the yolk, interesting commentary on Bialascewicz's researches 

 would be possible. It agrees with the earlier measurements of 

 Bellini, who found the electrical resistance of the unincubated white 

 to be Q. 1 8-8 ohms. Much further work on such properties of the 

 yolks and egg-whites of a wide range of eggs is urgently needed, for 

 they must obviously be of the greatest importance to the developing 

 embryo. Such questions as the electrical conductivity of egg-cells 

 and developing embryos are very relevant here, but must be left 

 for consideration in Section 5. 



As a conclusion to this discussion of the chemical constitution of 

 the egg, it may be admitted that great progress has been made in 

 our knowledge with respect to it during the last fifty years. But to 

 a discerning judgment, it remains none the less a matter for great 

 surprise that in view of our comparative ignorance of the chemical 

 architecture of the egg, we know as much as we do about the coming- 

 into-being of the chemical architecture of the finished embryo. 



One further matter may be alluded to in this section. The com- 

 position of fossil eggs cannot be said to have much embryological 

 interest, but it is hard to exclude a mention of them. The only 

 analyses we have are those of ZoUer who worked on the fossil eggs 

 of Chincha Island, off the Peruvian coast, where seagulls have been 

 living and depositing guano from a very remote date. Zoller found 

 that "time, which antiquates antiquities, and hath an art to make a 

 dust of all things" had had that effect on these eggs and had reduced 

 their water content to 14-4 per cent. There was no urea or uric acid 

 present, although the protein had nearly all disappeared and had 

 given rise to ammonium salts. There was no trace of fat or of carbo- 

 hydrate, and the sulphur of the proteins had all turned into sulphate. 



These figures make it only too clear that if palaeontology and bio- 

 chemistry enter into closer relations than exist at present, it will not 

 be by way of the chemical analysis of fossil eggs. More hopeful 

 approaches will be found in Section 9-15. 



