44 



Amoebae grown in cultures from amoebic ulcers, when stained by 

 Borrel's method, show somewhat different reactions. 



Cover-glass impressions may be made in the following way : 



A cover glass is placed upon the growths on agar plates, removed 

 quickly, and instantly plunged into a very hot saturated solution of 

 mercuric bichloride. It is then washed in Gram's solution or a 

 weak tincture of iodine and rinsed in 80 per cent alcohol, after 

 which it is washed in water. The stain is then applied in the usual 

 way. After this process the preparations are differentiated in 

 alcohol, cleared in xylol, and mounted in xylol-damar. The amoebae 

 are seen in various conditions, as they were in the culture, and of 

 various shapes and sizes. In many the pseudopodia have not been 

 withdrawn and can be well seen. Under these circumstances the 

 ectosarc has a pale, diffuse blue color, or is perhaps very finely 

 granular and has a very sharply differentiated limiting line. How- 

 ever, usually this is not well seen and the whole organism has a 

 sharply circumscribed, blue, granular appearance. The contractile 

 vacuole shows clearly as an imstained ovoid or oval space, usually 

 near the surface of the organism but occasionally near the nucleus. 



The nucleus is composed of a round, central, deep purple body, 

 surrounded by a narrow, pale-bluish, homogeneous zone, and this 

 in turn is surrounded by a denser, blue, granular one. About this 

 in turn is ordinarily a second more or less faintly stained zone. 

 The whole nuclear body is round or slightly oval. The nucleolus is 

 always round. 



Comparing the amoebae in such preparations with those in sec- 

 tions, we can readily see that the relative size of the nucleus is the 

 same, as is also the relation between the protoplasm and nucleus; 

 but in the tissues the contractile vacuole is usually not so distinct 

 and the nucleus does not present the same appearance. This may 

 be due to the fixation or it may be due to the different degree of 

 decolorization. The dissimilar nutritive conditions may also affect 

 the microchemical staining reactions. 



The small amoebae, having the size of an erythrocyte or smaller, 

 should show the same relation in the size of nucleus and cell body. 



The distinguishing features of the amoebae are their generally 

 irregular or oval shape (though they are often round), their rela- 

 tively small, round nucleus, and the larger amount of granular or 

 vacuolated protoplasm, which often contains foreign bodies. 



