20 E. J. LUND 



Experiment IV: Table 4- In this the procedure was the same as in 

 the previous experiment, but the animals were taken from a different 

 culture, and instead of 3 sets of 48 individuals each, 4 sets of 48 individ- 

 uals each were used. Each individual of Sets A, B, C and D were fed 

 1, 2, 3 and 6 grains, respectively. 



Four individuals (marked X in the table) of Set C extruded 

 part of the six grains and are therefore not counted in the results. 

 The temperature was 25 to 26°C. Examinations were made 

 ^, 5, 6i, 8, 9|, 11, 12i, 14, 15i 17, 18^ 20 and 22^ hours after 

 feeding. In this experiment the possible slight error in the 

 average time for complete digestion in Set C, Experiment III, 

 due to the approximation of the time of complete digestion in 

 some of these individuals, is eliminated, because observations 

 were made regularly throughout the whole 22| hours. And the 

 conditions were on the whole better than in Experiment III. 



The results of both experiments agree in showing that the aver- 

 age total amount of vitellin digested per unit of time is greater 

 in individuals fed a larger quantity than in those fed a smaller 

 one, i.e., this quantity is greatest in Set D > Set C > Set B > 

 Set A. 



The average time, found by experiment, for the complete 

 digestion of one grain or its equivalent in volume or mass, in the 

 sets of individuals of the preceding two experiments is given in 

 column 2 of table 5. 



Now if we establish a limiting case, by supposing that the 

 average quantity of vitellin digested per unit of time, is a func- 

 tion only of the amount of surface of the substrate exposed to the 

 action of the digestive agent, then we should expect to find 

 (provided further that the total surface of each grain in the 

 individuals fed more than one grain was exposed to the action of 

 the digestive agent), that individuals fed 6, 3 and 2 grains each, 

 would complete digestion of all in the same length of time as it 

 takes to digest one grain. Hence, if it takes 8.56 hours (Experi- 

 ment IV) to digest one grain, then in Sets B, C and D we should 

 expect to find that the quantity of vitellin equal to the volume 

 of 1 grain, would undergo digestion in the times shown in table 5, 

 column 3. 



