424 SPECIFIC MICRO-ORGANISMS 



Other individuals. The cell is 8 to 60/i in diameter. The ecto- 

 plasm is distinctly differentiated from the endoplasm even when 

 the cell is motionless, and the lobose pseudopodia are made up 

 entirely of the stiff highly refractive ectoplasm. _The endopla'fem 

 contains food material consisting of bacteria, cell fragments and 

 red blood cells. The nucleus is very distinctly visible in the 

 living ameba. It is spherical and surrounded by a- thick doubly, 

 contoured nuclear membrane. The chromatin is usually dis- 

 tributed just beneath the nuclear membrane 

 in largest amount and in the center there is a 

 karyosome with definite centriole. The vege- 

 tative multiplication takes place by division into 

 two daughter cells. Multiple division seems not 

 to occur. 



Pig. 184. — Enda- ^ , . . , , i rri i. 



mceba dysenteria. Lyst formation IS rarely observcd. 1 he cysts 

 5ntgfoTfnuTeI ^re most likely to be found when the stool be- 

 and a mass of chro- comes formed ill convalcsccncc from an attack of 



midial substance. i . , i \. i ^i -u 



{After Hartmann.) dysentery and they may then be very numer- 

 * ous. The mature cyst contains four nuclei,, 

 and frequently contains also one or more large masses of chromidial 

 substance which stain black with iron hematoxylin. 



The forms of the organism commonly observed in the feces of 

 dysentery are either the active vegetative cells^ or degenerating 

 forms, and the latter may lead to confusion unless their true nature 

 is recognized. 



The belief that amebae bear a causal relation to dysentery is 

 based upon the fact that certain types of amebae, E. dysmtericB 

 (E. Mstolyiica) are found in the stools, as a rule, only in cases of 

 dysentery; further, that these cases of dysentery, in which these 

 amebae occur, are characterized by definite clinical signs and 

 typical anatomical changes in the intestine ; and that these amebfe 

 are found penetrating deeply into the mucosa of the intestine, 

 and it is possible to produce ulcerative enteritis in experimental 



' Hartmann: Arch. f. Protistenkuniie, 1912, Bd. XXIV, S. 163-181. 



