AMOEBAE VERSUS TISSUE CELLS 7 



REACTION TO MELANIN PIGMENT GRANULES 



In studying the amoeba's reaction to melanin pigment gran- 

 ules, I first introduced the amoebae into tissue cultures of the 

 spleen which had been growing with the melanin pigment from 

 the retina of a chick embryo for from twenty-four to forty-eight 

 hours. Later I simply put the granules into hanging drops of 

 0.7 per cent normal salt solution with the amoebae. 



As soon as the amoebae recovered from being transferred and 

 were moving about with their large ectoplasmic pseudopodia, 

 they began to take in the pigment granules. The amoebae 

 reacted differently to these granules which were in great numbers 



Fig. 2 Amoeba stained with neuti'al red and janiis black no. 2. The neutral- 

 red granules are clear, the mitochondria are solid black. 12.5 ocular, 1.9 oil 

 immersion. 



Fig. 3 Amoeba stained with janus black no. 2. The mitochondria are oblong 

 and a few small ones are arranged in groups. 12.5 ocular, 1.9 oil immersion. 



and were showing brownian movement. Some of the amoebae 

 at once took in large numbers of the granules, others only a few, 

 and still others moved about freely among the granules without 

 taking in any of them. There was evidently some difference in 

 the physiological condition of the amoebae at that time. 



Alany of the granules were oblong, so that it was easy to deter- 

 mine their movement in the cells. They alwaj^s entered by way 

 of the anterior pseudopodium, whether it was one large pseudo- 

 podium or two smaller ones. The amoeba took in the granules 

 in the same manner that it takes in its food. The granules had 

 to be in the same plane as the advancing pseudopodium. If 

 they were above it or below it the amoeba simply went past it 



