30 E. J. LUND 



THE NATURE OF SOME OF THE FACTORS WHICH BRING ABOUT 



EXTRUSION 



1. Experiments with paraffin oil and olive oil 



If a conception can be obtained of what some of the dynamic 

 conditions of the cell are, by a study of the processes of intake 

 of foods and other substances, then we might expect to find that 

 the process of extrusion will serve as a valuable index in discover- 

 ing what some of the responses of the cell system are to those 

 same substances, after they have produced their effects from the 

 interior of the cell. Relations as interesting as those discovered 

 in feeding ought to be found by studying the phenomena of 

 extrusion, though the process, for various reasons, does not lend 

 itself so readily to experimental inquiry. 



I have shown (Lund '14) that when Biu-saria has been fed 

 Sudan III or Chinese ink alone, these substances are not retained 

 within the cell for any considerable length of time, and further 

 that if Bursaria is fed at the same time one of these substances 

 and vitellin, then the Sudan III or Chinese ink is extruded after 

 a short time, provided it has not come to be located in the same 

 vacuoles which contain vitellin; while the vitellin is retained, 

 digested and resorbed. In other words there exists a selective 

 extrusion among food vacuoles formed at the same time, or dif- 

 ferent times. Above (p. 24, table 6, a) it was further shown that 

 in the case of vitellin grains stained with congo red, a large num- 

 ber were extruded during digestion, or before any digestion had 

 taken place, while unstained grains were retained and digested 

 by the control individuals. Here the condition which brought 

 about extrusion can be only the presence of the absorbed dye, 

 i.e., a chemical condition. Since both sets of individuals were 

 fed one grain each, the size or shape of the grain had nothing to 

 do with the difference between the results. 



When both unstained grains, and grains stained with congo 

 red, were fed to the same individuals, similar results were ob- 

 tained. Further to test this by feeding two liquid substances 

 of somewhat similar physical properties, but of different chemical 

 nature, the following experiment was carried out. 



