120 PARASITIC AMOEBJE OF MAN. 



Color. I have already called attention to the dull 

 grayish color of Entamceba coli and to the lack of 

 differentiation between the ectoplasm and the endo- 

 plasm. In Entamceba Mstolytica the ectoplasm is 

 almost colorless and very ref ractile, resembling a piece 

 of ground white glass, while the endoplasm is of a 

 very light gray color, in many instances tinged with 

 green, due to absorbed haemoglobin. In cases in 

 which the stools contain blood, the majority of the 

 amoeba? observed show this greenish tint due, I be- 

 lieve, to haemoglobin liberated during the digestion of 

 the red blood corpuscles. That this is true can be ex- 

 perimentally demonstrated if one cares to spend the 

 time to do so. I have many times observed an amoeba 

 cross the microscopic field and engulf a red blood cor- 

 puscle and have watched the latter slowly disappear, 

 the endoplasm at the same time assuming a greenish 

 color. 



It is very common to observe not only well pre- 

 served red blood cells within this organism, but also 

 fragmented corpuscles, and in such instances it is 

 always noted that the endoplasm is distinctly green 

 in color. This phenomenon proves that Entamceba 

 Mstolytica is capable of engulfing and destroying the 

 red blood corpuscles of its host and serves to dis- 

 tinguish it from Entamceba coli, for in the few in- 

 stances in which I have observed red blood corpuscles 



