EFFECTS OF AGING UPON GERM CELLS. 



II 



group of them rectifies any such error, and gives an accurate 

 measure of the physiologic condition of the eggs. The determi- 

 nation by several or all of the tests serves as the most exact method 

 so far recorded, whereby the vitality of any batch of eggs may be 

 accurately ascertained and whereby the rate and nature of the manifold 

 changes, with age or under any set of experimental conditions, may be 

 determined. 



The correlated changes are given below in tabular form. 



This remarkably close correlation of the various changes 

 associated with aging may be expressed graphically as in Fig. i. 

 The ordinates represent the degree of change or physiologic 

 deterioration, the abscissas represent age of eggs. There are a 

 number of independent tests which demonstrate unequivocally 

 that freshly liberated eggs (in good physiologic condition) 

 improve with age, and after a definite period begin to deteriorate. 

 Such eggs upon liberation produce their membranes increasingly 

 fast, and cleave more rapidly, and with increasingly large per 

 cents, as the eggs become older. This gradual improvement or 



