SECT, i] PHYSICO-CHEMICAL SYSTEM 359 



do not go below unity, though they approach it much more nearly 

 than do the fishes. Further work is needed to clear up this contra- 

 diction. In one case, however, Bialascewicz got a ratio below unity, 

 that of Arenicola claparedii, so that in a general sense his investigations 

 are not opposed to those of Page and Konig & Grossfeld. McCallum's 

 low ratio for the egg of the herring is difficult to explain, but 

 Perugia's analysis of the egg-jelly of ovo viviparous selachians fits in 

 well enough with the majority of the other evidence. Attention might 

 also be drawn to Bialascewicz's high ratio (15) for the eggs of the 

 octopus. Sepia, which would appear to be extraordinarily poor in 

 metallic ions (cf. p. 317, Section 13 and the Epilegomena). 



Some further light is perhaps thrown on the inorganic composition 

 of eggs by Wetzel's figures for insoluble and soluble ash. He sub- 

 mitted the eggs of various animals to examination, with the following 

 results : 



% dry weight 



Species Total ash Insol. ash Sol. ash 



Sea-urchin {Strongylocentrotus lividus) ... 9-7 2-4 7-2 



S^iideT-cvah {Maia squinado) ... ... 4-12 0-27 3-8 



Octopus {Sepia officinalis) ... ... ... 2-2 0'59 i'6 



Tio^sh. [Scyllium canicula) ... ... ... 5-5 1-15 4-3 



In all cases he found more soluble than insoluble salts, i.e., more 

 chlorides than sulphates and phosphates. 



Table 48. Bialascewicz' s figures. 



It is very interesting, as Bialascewicz points out, that the mineral 

 composition of terrestrial and aquatic animals should be so alike. 

 The preponderance of potassium which is seen in the hen's tg^ does 

 not change as one passes to organisms laying their eggs in an environ- 

 ment containing far more sodium than potassium. Thus, although 



