70 A. A. SCHAEFFER 



begun, but not completed. The food stimuli proceeding from 

 aleuronat do not seem to affect amebas as intensely as those 

 arising from gluten or globulin. All amebas sense aleuronat at 

 a distance and usually move toward it and frequently into con- 

 tact with it. In consequence the direction of movement is often 

 changed. The digestibility of aleuronat has not been tested. 



EXPERIMENTS WITH LACTALBUMIN 



The lactalbumin used in these tests was coagulated in the proc- 

 ess of preparation and may therefore be regarded as insoluble in 

 water. 



Sixteen experiments with lactalbumin as the test substance 

 were performed upon a granular ameba. Previous to these ex- 

 periments the ameba ate a piece of globulin and also a grain of 

 keratin, but the keratin was excreted a few minutes after its 

 ingestion. Following several other experiments with keratin, 

 there was placed in the ameba's path a grain of lactalbumin (695). 

 The ameba avoided it and moved on. The lactalbumin was 

 then shifted so as to lie again in the ameba's path (699). The 

 ameba moved directly forward, showing that it was attracted 

 somewhat, or at least not repelled, by the lactalbumin. The 

 ameba came into contact with the test substance at the side and 

 partly passed by it, but two side pseudopods w^ere then sent out 

 against the lactalbumin. These formed a large food cup in 

 which the lactalbumin was slowly ingested. The ameba then 

 became comparatively quiet for about two minutes. Five min- 

 utes after the formation of the food cup the lactalbumin was 

 egested, the ameba moving off in the original direction (707). 

 A few minutes later a new piece of lactalbumin was laid in the 

 ameba's path (708). The ameba moved forward passing the 

 lactalbumin on the right for a short distance. A typical food 

 cup was then formed in a manner not quite like the first, in 

 which the lactalbumin was ingested (713). The ameba remained 

 comparatively quiet for a few minutes. About seven minutes 

 after the formation of the food cup the lactalbumin was excreted 

 (718). A fresh piece of lactalbumin was then placed ahead of 

 the ameba (719). The ameba moved directly into contact with 



