CHAPTEK LI. 



CLASSIFICATION AND MORPHOLOGY OF AMEB A CULTIVATION- 

 PATHOGENIC AMEBA ENTERO-HEPATITIS IN 

 TURKEYS BALANTIDIUM COLI. 



AMEBA. 



Morphology. Ameba is a genus of protozoa belonging to the class 

 of rhizopoda of the subphylum sarcodina. The name is derived 

 from a Greek word which means change, indicative of the fact that 

 amebse are protozoan organisms which, under favorable conditions, 

 constantly change their form. This is brought about by currents in 

 their protoplasm and by the formation of processes extending from 

 the periphery. These processes, which are called pseudopodia (false 

 feet), serve as organs of locomotion. If an ameba is suspended in a 

 fluid it is likely to send out short pseudopodia in every direction. As 

 soon as one pseudopodium touches a small solid particle the other 

 pseudopodia are drawn in and the remaining one elongates and draws 

 the whole organism toward the particle to which it has fastened itself. 

 If amebse are studied on a slide under the microscope it can be 

 seen how they always draw their body along on a pseudopodium 

 extending out from the periphery. The motion is a very peculiar one. 

 It is really not so much a drawing of the protoplasm as a flowing 

 of the latter in the direction of the outstretched pseudopodium, which 

 is generally lobose or lobular in shape. Amebse generally exhibit 

 a round or oval, more or less vesicular nucleus. The chromatin is 

 distributed along the periphery of the nucleus and the interior shows 

 a central granule. The protoplasm of amebse is generally more or 

 less finely granular and very frequently contains one or more con- 

 tractile vacuoles which preferably empty their fluid toward the outside. 

 The cytoplasm is generally differentiated into an entoplasm, and an 

 often strongly hyalin, ectoplasm. Multiplication of amebse occurs 

 either by fission with an amitotic division of the nucleus, or the 

 ameba may become encysted, forming in its interior a number of 

 young amebse which, after rupture of the cyst membrane, are set 

 free and grow rapidly. Spore formation has also been observed. 

 This is preceded by the expulsion of chromidia or idiochromidia 

 from the nucleus into the cytoplasm. Small masses of chromatin 

 reach the periphery, are extruded from it, and finally cut off with a 

 small amount of protoplasm. From these spores young amebse are 

 developed. Amebse are found in the outside world and in moist 

 soil, where they lead a purely saprophytic existence, or they may be 



