PLATE 1 



EXPLANATION OF FIGURES 



Typical stages in the process of digestion and resorption in a food vacuole 

 of Bursaria containing a single grain of fresh yolk or vitellin. 



A Degree of acidity attained by the vacuole as shown by litmus at time of 

 separation from the end of the gullet. The pink edges indicate that acid has 

 been secreted from wall of gullet; figures B and C, further stages in same process. 



A to E, inclusive, show course of resorption of liquid enclosed during formation 

 of vacuole. 



G to L, inclusive, typical stages of digestion and resorption of fresh yolk 

 (protein and lipoid). 



G and H' to L', inclusive, typical stages in digestion and resorption of vitellin- 

 liquid present in the vacuole. 



G and H" to L", the same as H' to L' except that products of digestion are 

 resorbed as soon as they are formed. Change indicated by figures under x lasted 

 on the average 38 seconds; change shown by figures under y about 4§ to 6 minutes. 



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