412 AGRICULTURAL AND INDUSTRIAL BACTERIOLOGY 



Human trypanosomiasia or sleeping sickness is caused by 

 the Trypanosoma gambiense. This disease has made 

 uninhabitable a considerable section ' of north, central and 

 eastern Africa. It is transmitted by means of one of the 

 tsetse flies. It is probable that the organism is present in 

 certain of the wild animals in this region. In the first stages 

 of the disease the organisms can be found in the blood. 

 Later pains in the back develop and the patient becomes 

 drowsy, sinks into a coma from which he cannot be readily 

 aroused and finally dies. The disease is chronic ; sometimes 

 several years elapse before it proves finally fatal. 



A disease known as murrina in the horse in Panama, 

 Venezuela, and Central America has also been traced to a 

 Trypanosoma. 



THE GENUS ENTAMCEBA 



An ameba which is found as a normal inhabitant of the 

 intestinal tract in man is known as Entamceba coli. An 

 organism somewhat resembling it and causing so-called 

 amebic dysentery is termed Entamceba histolytica. The 

 genus Entamceba differs from Amoeba in the absence of con- 

 tractile vacuole and by the formation of multinucleated cysts. 



The Entamceba histolytica, the cause of amebic dysentery 

 may be observed in the stools of those who are suffering 

 from the disease as a mass of protoplasm without definite 

 cell wall and possessing a definite nucleus. It moves about 

 by means of the protrusion of blunt pseudopodia. It is 

 either colorless or slightly tinged with green due to the 

 presence of hemoglobin from blood corpuscles which have 

 been engulfed. The inner portion of the protoplasm ( endo- 

 plasm) and the outer portion (ectoplasm) may be readily 

 differentiated in that the latter is hyaline, glasslike and 

 more refractive. Reproduction of the organism is accom- 

 plished in two ways. In the first method the nucleus frag- 

 ments into a number of nuclei which gradually collect under 



