Amebic Dysentery 641 



EXPLANATION OF FIG. 261 



(All figures drawn by Charles F. Craig, M. D. ) 



III. Upper Group. Entamoeba tetragena fixed in sublimate alcohol and stained 



with Delafield's hematoxylin. Note the great delicacy of the stain- 

 ing when compared with the staining with the Giemsa method. 



A. A vegetative parasite showing three erythrocytes in the cytoplasm and a 



nucleus in which the nuclear membrane, and the karyosome with its 

 centriole are shown. 



B. A vegetative organism showing thick nuclear membrane and karyosome 



containing a centriole. 



C. A vegetative parasite containing vacuoles and nucleus showing karyo- 



some containing a centriole surrounded by an unstained area. 



D. A degenerative form filled with vacuoles and showing abnormal appear- 



ance of the nucleus. 



E. Precystic form of Entamceba tetragena. 



G. Another precystic form which is more typical in the free chromatin in the 

 cytoplasm is visible. The form E would probably degenerate before 

 the cyst wall was fully formed. 



F. A cystic form of Entamoeba tetragena showing two chromatin spindles in 



the cytoplasm and a nucleus having a centriole surrounded by an 



unstained area and a definite network upon which are arranged dots of 



chromatin. 

 H. An encysted form showing a very large mass of chromatin and a nucleus 



containing a karyosome and centriole. 



7. Two-nucleated cyst of Entamceba tetragena showing mass of free chroma- 

 tin and the morphology of the nuclei after division. 

 K. Fully developed cyst of Entamceba tetragena containing four daughter 



nuclei and a mass of chromatin. 

 L. Degenerated form of Entamceba tetragena containing some free 



chromatin and a nucleus in which the karyosome stains deeply and 



nearly fills the nucleus. This form might be mistaken for a free living 



ameba. 

 M. Illustrating the typical nuclear structure of Entamoeba tetragena. 



Note the large karyosome containing a centriole surrounded by an 



unstained area. 

 Lower Group. Entamceba histolytica fixed in sublimate alcohol and stained with 



Delafield's hematoxylin. 

 A and B. Vegetative organisms showing vacuoles and typical morphology of 



the nucleus. No distinction between the endoplasm and ectoplasm. 



C. Vegetative form of Entamceba histolytica showing the type of mitosis 



during simple division. 



D. First step in the formation of spore cysts. The distribution of the chro- 



matin by the nucleus to the cytoplasm. 



E. F and H. Organisms showing chromidia in the cytoplasm arranged in 



rods, threads, and masses, the nucleus being flattened out against the 

 periphery and staining poorly. 



G. A degenerative form of Entamceba histolytica filled with vacuoles and 



with an atypical nucleus. 

 / and K. Budding of the spore cysts from the periphery of Entamceba 



histolytica. 

 L. Illustrating the typical nuclear structure of Entamceba histolytica. 



IV. Upper Group. Entamceba tetragena stained with Giemsa stain. 



A, B, C. Vegetative organisms. Note that the nuclear membrane and 

 karyosome stain very heavily and are not as well differentiated as in 

 specimens stained with hematoxylin. 



D. Precystic form containing masses of chromatin in the cytoplasm. 



E. Degenerative form containing vacuoles, masses of chromatin, and an 



atypically stained nucleus. 



F. Two-nucleated stage of the cyst of Entamceba tetragena, showing heavy 



staining of the nuclear membrane and karyosome.- Two masses of 

 chromatin are present. 

 41 



