OF THE ALIMENTARY TRACT 99 



invisible. It is seen unstained as a refractive ring 

 of granules, and the number of nuclei may be com- 

 monly counted in the living cyst. This, however, is 

 facilitated by the iodine preparation previously de- 

 scribed. The particularly important and practically 

 useful point about the cyst is that any amoeba in the 

 stool developing a cyst with more than four nuclei 

 is not Endamoeha histolytica. Let medical labora- 

 torians adhere to this point as an anchor. 



Stained by the iron-haematoxylon procedure the 

 nucleus of both active and encysted forms is round, 

 has a definite rim, to which rather large chromatin 

 particles cling in irregular distribution. The karyo- 

 some is large and not in the center, although it may 

 appear so when the cyst is viewed in a certain expo- 

 sure. It is eccentrically situated. This body is com- 

 pact, although, unless Councilmania is valid, it may 

 appear as a group of small granules, and it is sur- 

 rounded by a ''halo." The nuclear network shows a 

 few granules of chromatin to the expert examiner. 



It may, therefore, be readily seen that to the ex- 

 perienced there are morphological differences between 

 the nuclei of Endamoeha coli and Endamoeha histo- 

 lytica upon w^hich positive differentiation may be 

 made. To the inexperienced observer these features 

 are not so clear and unless they are they furnish no 

 help in diagnosis. 



In iron-haematoxylon stained specimens the tro- 

 phozoite is seen beautifully prepared for observation 

 of it parts and ingested food. 



