74 A. A. SCHAEFFER 



food cup. The ameba became much less active after ingestion 

 of the globuHn. Movement was slow and somewhat irregular. 

 Another piece of lactalbumin was then laid near the ameba (896). 

 The ameba moved into contact with it and then the beha\dor 

 became very irregular. The lactalbumin was once partly sur- 

 rounded, but was finally left behind as the ameba moved on. 

 A few minutes later another piece of lactalbumin was placed in 

 the path of the ameba (904). The ameba moved directly for- 

 ward into contact with it and formed a typical food cup in which 

 it was ingested. Without quieting down, a pseudopod was 

 thrown out on the right, which elongated to a considerable ex- 

 tent. The posterior end then became active. Finally after 

 some minutes the ameba, in spatulate form, moved away in the 

 original direction. 



Summary of reactions to lactalbumin 



The experiments described above were performed on two granu- 

 lar amebas, both coming from the same culture. Both of these 

 amebas readily ingested lactalbumin, but they differed in the 

 length of time the ingested lactalbumin grains were retained. 

 Both amebas retained globulin. The first ameba retained no 

 lactalbumin, the second all that was eaten. But the contrast in 

 this respect between the two amebas is not as significant as 

 might appear. The second ameba seemed disturbed after the 

 ingestion of the last two grains of lactalbumin. The original 

 direction of locomotion was changed so that the lactalbumin 

 came to lie at once in the posterior part of the ameba. This is 

 particularly noticeable in figures 908 to 911. It may be concluded 

 therefore that the tendency to get rid of the lactalbumin was 

 present in the second ameba, although it was not sufficiently 

 strong to cause excretion. It should be pointed out that the 

 first ameba seemed to become disturbed by the ingested globu- 

 lin (808 to 812) and that the second ameba did not eat the globu- 

 lin with great readiness. It appears then that the stimuli induc- 

 ing feeding are considerably less intense in lactalbumin than in 

 globulin, and that after ingestion these stimuli seem to have 

 but slight effect on the endoplasm and in some cases no effect, 



The digestibility of lactalbumin has not been tested. 



