RELATIONS OF BURSARIA TO FOOD 



13 



The points of origin of acid as well as the rate of acidification 

 of the vacuole contents was determined. Table 2 gives typical 

 records of the total time for completely acidifying grains in 

 fifteen out of fifty individuals which were fed with fresh yolk 

 stained in blue litmus. No noticeable difference existed between 

 the acidification of fresh yolk and that of vitellin. The time in 

 seconds which it took to change completely the blue litmus- 

 stained grain to red, is given by the numbers underneath the 

 number of the individual. The average of the observations in 

 table 2 is 38 ± seconds. 



TABLE 2 



Total time in seconds for acidifying fresh yolk grains stained in blue litmus. The 

 table shows typical records of fifteen out of fifty individuals in which the time for 

 acidification of each grain was taken. The grains which are represented by the 

 numbers opposite to the brackets were included in the same vacuole. The other 

 numbers, not opposite brackets, represent grains, each of which were in a separate 

 vacuole, i.e., swallowed separately 



1st grain 

 2d grain 

 3d grain 

 4th grain 

 5th grain 

 6th grain 

 7th grain 

 8th grain 



INDIVIDUAL NUMBER 



20 



25 20 65 

 20 15* 40 



15 80 



15 



20 



3o: 



20' 

 180| 



9 10 11 



45 60 80 45 15 fSO 

 40 10 30 20 30 ■! 30 



50 20i 30 



25 



60 



45 

 60 

 50 

 40 

 60 



[35 55 

 35 30 



25 



It was evident that the time of acidification depended mainly 

 if not solely upon three conditions, as follows: (a) the size of 

 the grain; the larger the grain, other things being equal, the 

 longer it took for the last trace of blue color to disappear. For 

 example; grain number 8 of individual number 5, table 2, was a 

 very large grain; while grain 2 of individual number 8 was very 

 small, hence the difference in time, (b) The physical consistency 

 of the grain must be assumed to determine its permeability and 

 hence its time of acidification, (c) The concentration of the acid 

 secreted into the vacuole. 



