SECT. I] PHYSICO-CHEMICAL SYSTEM 357 



to see if they would grow richer in glycogen. They all did; in fact, 

 he was able to double their glycogen content by this simple means 

 (glucose acted better than sucrose, sucrose than lactose, and lactose 

 than glycerol, though even the latter substance gave an effect) . These 

 curious observations have never been confirmed, and can hardly be 

 said to carry conviction as they stand. Diamare obtained discordant 

 results in his researches on the sugar of various eggs ; thus, he got a 

 rather low value for the free glucose of the egg of Testudo graeca, but 

 none at all, either free or combined, from the eggs of Scyllium catulus 

 or Torpedo marmorata. No explanation can be given for this fact. In 

 connection with carbohydrates, it should be remembered that viper 

 venom, which is in all probability a glucoside, has been shown by 

 Phisalix to be present in active form in the yolks of viper eggs. 



i-i6. Ash 



We come now to the inorganic substances of eggs. Iron has been 

 shown to be present by microchemical tests in many eggs, such 

 as those of Limnaea, Tubifex, Rana esculenta (where it is massed 

 at the Ught ventral pole) and Pisidium, by the work of Schneider. 

 Dhere found traces of iron and copper in the eggs of Sepia. Warburg 

 found 0-02 to 0-03 mgm. iron per 100 mg. nitrogen in the unfertiUsed 

 sea-urchin egg ; part of it seemed to be in ionic form and part not. 

 According to Wilke-Dorfurt, there are 4-8 mgm. per kilo iodine in 

 oyster egg-shells. 



Ash analyses of eggs have been made by several workers, whose 

 results, it may be remarked, would have been more easily comparable 

 if they had expressed them in the same way, instead of in nine or 

 ten different ways, omitting in some cases the figures which would 

 enable them to be calculated into a form comparable with each 

 other. Table 47 summarises what is known about the distribution 

 of inorganic substances in eggs. It has entailed a good deal of calcula- 

 tion, for only one of the previous investigators expressed his results 

 in terms of millimols and milliequivalents, and unless this is done it 

 is impossible to gain any idea as to the relative preponderance of 

 cation and anion. The first thing which should be noted is the 

 fact that, when the salts are expressed in per cent, of the total 

 ash, potassium is always there in greater amount than sodium, and 

 nearly always to a greater extent than any other metal. This seems 

 to be quite characteristic of the ovum, though in other systems of 



