RELATIONS OF BURSARIA TO FOOD 



35 



occur was not, in part at least, due to complete digestion and 

 resorption of the missing grains. But this difficulty *is almost 

 wholly avoided in this experiment, because the process of diges- 

 tion and complete resorption of fresh yolk is much slower than 

 that of vitellin alone. This is mainly due to the fact that the 

 fat of the fresh yolk is digested and resorbed at a slower rate than 

 the vitellin of the yolk grain (cf . plate 1, figs. H-L, and figs. H'-L') . 

 This fact is further shown in the records of the total numbers 

 of grains present in Set A, table 7, for twenty individuals out of 

 forty-eight, still contained remains of the one grain fed thirty 

 hours previously, this should be compared with the average 

 time for digestion of one grain of vitellin in Experiments III and 

 IV, table 5, column 2. Now, from these facts regarding the 

 difference in rates of digestion of one grain of vitellin and fresh 

 yolk, it is not to be expected that the individuals of Sets B and C 

 would show as rapid a rate of digestion as if they had been fed 

 an equal number of grains of vitellin; and therefore it becomes 

 clear that if the comparatively small total number of grains pres- 



TABLE 7 



Summari/ of results of Experiment VIII {January 24, 1913) showing the effect of the 

 quantity of fresh yolk eaten, upon the course of the extrusion reaction in Bursaria. 

 Three sets of forty-eight individuals each xvere used. Each individual in the Sets 

 A, B and C, was fed 1, 3 and 6 grains, respectively 



HOURS AFTER PEEDINQ 



14 16 24 I 30 



Set A. Forty- 

 eight Indi- 

 viduals fed 

 1 grain each 



Total number of grains 

 present 



Per cent present of to- 

 tal number of grains 

 fed 



48 



100 



47 I 46 



.9-1- 95.84-170. 8-f- 



32 



32 I 32 



.6-f,66.6-|-66.6-l- 



30 



62.5-t- 



56.3 41.6-h 



Set B. Forty- f Total number of grains 



eight indi-J ; present j 144 j 137 j 97 j 44 44 43 



viduals fed! \ Per cent present of total ! 



3grainseach[ number of grains fed. 100 95. l-f- 67. 34-30. 5-1- 30. 5-|- 29. 8-1- 



31 



29 



21.5+ 10. 1-f- 18. 7-1- 



19 

 13.2 



Set C. Forty- [ Total number of grains \ 



eight Indi- \ present 



viduals fed \ Per cent present of total 



manj'grains I number present at 



each I three hours ' 



100 



165 



81.1-1-60.8-1- 



36.1-1- 



49 



18.0 



30 



11.0 



26 



9.5 



6.2+ 



3.7 



