RELATIONS OF BURSARIA TO FOOD 31 



Experiment VII, a, h and c: (figs. 5, 6 and 7) . Emulsions of paraffin oil, 

 and olive oil were made in tap water. The animals were starved as usual 

 in tap water. 2 cc. of this tap water was placed in each watch glass and 

 used as a medium, so as to prevent any effect due to transfer from this 

 into fresh tap water. Set A consisting of 48 individuals that had eaten 

 olive oil were picked out from the 8 cc. with olive oil emulsion in which 

 they had been feeding for 10 minutes. Another set, B, of 48 individuals 

 that had been fed an emulsion of paraffin oil were picked out at the same 

 time. Both sets of individuals were washed in some of the tap water in 

 which they had been starved. After washing, two individuals were 

 placed in each watch glass, the latter being kept in moist chambers. 

 The moist chambers were placed in a constant temperature oven kept 

 at 25 to 26°C.^ — an unnecessary precaution for the purpose of the 

 experiment. Records were taken at the time intervals given by the 

 points on abscissae in the curves. 



The process of extrusion was gradual, i.e., all the paraffin oil 

 present in an individual was not usually extruded at the same 

 time. Small globules or traces generally remained for various 

 lengths of time after the main bulk of the oil had been extruded. 

 Since there was no way of expressing the course of this process 

 quantitatively, when oil was used, the time when all trace of oil 

 in the food vacuoles had disappeared was taken as the time of 

 extrusion, for comparison in the two sets of individuals, A and B. 

 Hence the curves are based on the time for complete extrusion. 

 As a matter of fact, the difference in the time of extrusion between 

 Set A and Set B was actually greater than the curves show, for 

 the bulk of the paraffin oil was extruded, on the average, consider- 

 ably earlier than that of the olive oil. 



The experiment was carried out three times, all giving con- 

 cordant results, as shown by curves, figures 5, 6 and 7. In no 

 individual in the above experiments was the disappearance of 

 olive oil due to retention and complete digestion. Fats are 

 resorbed very slowly. The material came from three different 

 wild cultures, otherwise the procedure was the same in all, "The 

 extrusion reaction was apparently not as effective in Experiment 

 VII, b (fig. 6) as in the others. 



Tests for fat content showed marked resorption in those 

 individuals which had retained some or all of the olive oil for some 

 time after feeding. No increase in the fat (oil) content could be 

 seen to have taken place in individuals of Sets B fed paraffin oil. 



