EFFECTS OF AGING UPON GERM CELLS. 379 



0.3, 2.7, 0.7, 0.9, 0.4 per cent., with an average of 0.81 per cent, 

 loss per hour. In the second group with physiologically poor eggs 

 the loss was, i.o, j-5, 2.8, j.j per cent, per hour with an average of 

 2.65 per cent, or over three times as rapid. I cannot account for 

 the only apparent exception, namely female 5, whose rate of loss 

 was 2.7 per cent. 



Fig. i represents the loss of jelly with age. With physio- 

 logically good eggs, the numbers with jelly is a maximum or 

 nearly so, and the rate of loss with age is small, part a and B. 

 As the eggs become physiologically poor, and in eggs which were 

 in poor physiologic condition at the time of liberation, the 

 numbers with jelly is much less, and the rate of loss with age is 

 more rapid, parts C, D, etc. It should be noted in passing that 

 parts B, C, D and E, are parallel with the corresponding parts of 

 the curve showing change in the volume of eggs with age. 



The observations upon Arbacia eggs are in entire accord with 

 those of Hipponoe. They differ only in the slower rate of loss. 

 One example may illustrate this slower rate. The eggs when 

 freshly removed showed 90 per cent, with their jelly layers. 

 When 41 hours old, 50 per cent, possessed the layer, when 46 

 hours, 19 per cent., when 70 hours, I per cent., and when 72 

 hours none of the eggs possessed the jelly layer. In both species 

 of eggs the loss of jelly was a function of age, and physiologic con- 

 dition at time of the first observation. If the loss of jelly is known, 

 one can predict (provided proper precautions are taken) the 

 physiologic condition of the eggs and vice versa, from the physi- 

 ologic condition one may determine the loss of jelly. 



Loeb, Harvey and F. R. Lillie in particular, as well as others, 

 have recorded the loss of jelly in old eggs. My observations 

 show not only a loss with age, which is different for different 

 species, but I have determined the rate of loss with age. More 

 than this, I have shown that the rate of loss depends not only 

 upon the species and temperature, but upon the condition of the 

 eggs at liberation, and finally that loss of jelly serves as another 

 symptom of the physiologic condition or vitality of the eggs at 

 any time, and that th!s vitality diminished at a known rate with 

 age. 



