

2O A. J. GOLDFARB. 



ion concentration be made, the loss of jelly is concomitant with 

 physiologic deterioration or aging of the eggs. 



The second and more important change is concerned with the 

 cortical layer of the egg. With age the dissolution of membrane- 

 forming substances progresses and the permeability of the cortical 

 layer increases, as a consequence of which a number of other 

 changes occur, namely: (i) An inflow of sea water and an increase 

 in size of the egg; (2) increasing mechanical interference due to 

 the excess sea water; (3) thinning and final disappearance of 

 fertilization membrane; (4) gradual solution of protoplasmic 

 granules; (5) increasing viscosity of the cytoplasm; (6) increasing 

 metabolism and metabolic products. 



By aging is meant the ensemble of these and other changes in 

 the egg. 



It is not to be wondered then that with protecting jelly, 

 cortical layer, cytoplasm and probably nucleus as well, chemically 

 and physically altered, profoundly altered in some instances and 

 entirely gone in others, that the subsequent history of the egg 

 should show evidences of these changes, and be correspondingly 

 altered in development. These changes in development may be 

 categorically summarized as follows: (i) Increasing retardation 

 and final loss in membrane formation; (2) increasing modifi- 

 cation in character of membrane; (3) increasing retardation and 

 final cessation of cleavage; (4) increasing irregularity in cleavage; 

 (5) increasing viscosity of cytoplasm and cortical layer; (6) in- 

 creasing agglutination and fusion of eggs; (7) increasing sepa- 

 ration of the blastomeres; (8) increasing modified larvae, etc. 



The problem of physiologic deterioration or "aging" is 

 reducable then to two main factors (i) a change in permeability 

 of the cortical layer, (2) a change in the metabolism of the egg. 

 I have already outlined the nature and conseqences of the first of 

 these two factors. A few words may be added concerning the 

 second. 



Loeb's researches on oxidation of eggs had led him to the con- 

 clusion that with "aging," the eggs had increasing difficulty 

 in disposing of the accumulated store of toxic metabolic products. 

 Wasteneys' subsequently by direct experimentation showed that 

 there was a definite increase in metabolism with aging of eggs. 



