IO A. J. GOLDFARB. 



In Arbacia it was much slower. Beginning, in the given experi- 

 mental conditions, in about 28 hours as in experiment 17, and 

 extending to 42 hours as in series 19, 46 hours in experiment 18, 

 and later in other experiments. This difference in rate of 

 cytolysis is in part due to differences in temperature of the sea 

 water in the two localities, but it is also due, and is another evi- 

 dence of, a protoplasmic difference in the two species of eggs. 



CORRELATION OF THE CHANGES IN AGEING EGGS. 



I have for the sake of clearer exposition described each type of 

 change in aging eggs, such as agglutination, irregular cleavage, 

 etc., as though each type of change was independent and un- 

 related to the other changes. / wish now to emphasize the en- 

 tirely dependent, related and con-elated character of the changes I 

 have heretofore treated separately. 



Seven types of changes and tests have been enumerated, 

 whereby the- physiologic condition of the eggs may be accurately 

 determined. These tests are (i) size of the egg, (2) per cent, 

 possessing jelly layer, (3) rate and width of membrane, (4) rate, 

 total and character of cleavage, (5) rate and degree of aggluti- 

 nation, (6) rate and degree of fusion of eggs, (7) and per cent, 

 of cytolysis. Each test serves as a verifiable measure of quali- 

 tative and quantitative changes in the vitality or physiologic con- 

 dition of the eggs under the given conditions. 



But more significant for my present purpose is the fact that 

 the variation in any one of these seven tests is associated with 

 corresponding variation in the others. So highly correlated are 

 they that a knowledge of one enables one to predict with a remarkable 

 degree of exactness, the degree of variation in the others. If the 

 cleavage rate for example, is known, one could predict the size of 

 the eggs, the per cent, with jelly layers, the rate of fertilization 

 membrane, the per cent, of agglutination, etc. This somewhat 

 sweeping statement is made with the understanding that it is 

 subject to the qualifications referred to in the text. 



It is sometimes inconvenient or difficult to take certain pre- 

 cautions with respect to one or another of the seven groups of 

 tests, and without such precautions any one test may give a 

 large error. But the ensemble of the tests or any considerable 



