14 PARASITIC AMGEB^E OF MAN. 



primitive organs which will be mentioned in the gen- 

 eral description. 



THE CYTOPLASM. The body of an amoeba is 

 composed of a mass of cytoplasm varying in appear- 

 ance and structure in different species. As a rule, 

 two distinct portions of this substance may be recog- 

 nized, an outer portion, known as the ectoplasm and 

 which comprises the smaller portion of the cytoplasm, 

 and an inner portion, known as the endo plasm. It is 

 in the latter portion that the nucleus lies imbedded. 



The ectoplasm may be well or illy defined from 

 the endoplasm, and in some species is seen to be 

 composed of minute granules, while in others it ap- 

 pears structureless. In some, the ectoplasm is grayish 

 in color and veil-like in appearance, while in other 

 species it is glass-like in appearance and dense in 

 consistence. Thus in Entamceba coli the ectoplasm 

 is difficult to distinguish from the endoplasm and is 

 of very delicate consistence, while in Entamceba his- 

 tolytica the ectoplasm is very distinct, glass-like in 

 appearance, and dense in structure. In some species 

 the ectoplasm can only be differentiated when the 

 organism is in motion, while in others it is impossible 

 to differentiate it at any time. In a few instances the 

 ectoplasm contains coarse granules, the nature of 

 which is unknown. 



The Endoplasm. In all species of amcebse, if a 



