THE PROBLEM AND METHODS OF INVESTIGATION 79 



There is no difficulty in distinguishing between these five stages 

 with sufficient exactness for all purposes. Where the differences 

 in rate of metabolism between two animals or lots are great, they 

 are clearly shown by the times of the beginning and completion of 

 disintegration in each lot, but by following the different stages of 

 the process it is possible to distinguish slight differences. As re- 

 gards length of time, the different stages are not strictly comparable 

 in all cases; in large animals, for example, Stage III extends over 

 a somewhat longer time than the other stages, because the progress 

 of disintegration along the margins in the posterior direction 

 requires a longer time than in small animals and pieces where the 

 length of the margins is much less. 



In comparing susceptibilities determined at different times 

 with different solutions, great care is necessary, for slight differ- 

 ences in alkalinity of the water alter the susceptibility very con- 

 siderably, and susceptibility also varies with the temperature. In 

 order to avoid these and other complications, whenever possible 

 susceptibilities to be compared should be determined at the same 

 time, with the same solution, and under the same conditions of 

 temperature and light, etc. 



Table I will serve as an example of the method of recording the 

 observations and of the results obtained. In this table, the first 



TABLE I 



