828 BIOPHYSICAL PHENOMENA [pt. iir 



that the resistance of the cell-interior was hardly affected, but that 

 the resistance of the cell-membranes was definitely less than normal. 

 When these experiments were extended so as to include embryos, 

 the interesting figures shown in Table 96 were obtained. Throughout 

 embryonic life, the resistance of the embryonic tissues is obviously 

 less than that of the tissues of the maternal organism but, by the 

 time that birth is reached, the two are at an equality, or the reverse 

 relation may even be present. After the birth of the embryo the 



Table 96. Electrical resistance of liver cells. 

 Mendeleef 's figures. 



maternal liver tissue returns within 48 hours to its normal level. 

 Mendeleef concluded from all this work that the membrane per- 

 meability as well as the electrolyte concentration in the cytoplasm 

 were higher in the embryo than in the adult, and probably 

 higher the younger the embryo. We have had already a good 

 example of the increase of electrical resistance with age in the 

 work of Gayda (see Fig. 202). Evidently the electrolyte-content of 

 a tissue or an embryo is not measured by its ash-content, yet it is 

 not without significance, perhaps, that the ash-content of the chick 

 embryo (see Fig. 402) and of the frog embryo (see Fig. 230) decreases 

 with age. A striking illustration of this is provided by Fig. 249, 

 which shows the behaviour of the inorganic substance/organic sub- 

 stance ratio for the chick embryo, a ratio which falls steadily from 

 the beginning of incubation till the end. Mendeleef laid special 

 emphasis on the importance of the placenta in separating two 

 organisms with very different cellular permeabilities. She went on 

 to study the effect produced by keeping the extirpated tissues in 



