SARCODINA 737 



red blood cells. The nucleus is small, and in fresh specimens is usually 

 invisible. 



Before encysting the parasites are much reduced in size, and the 

 cytoplasm frees itself from all inclusions and becomes clear, spherical 

 and immobile. The cysts are small, eight to ten microns, circular and 

 definitely outlined, sometimes with a double contour, and in stained 

 specimens the nucleus is always visible. It is small, averaging only 

 three microns (Craig), making it smaller than in histolytica and coli. 

 The limiting membrane, while not heavy, is distinct, and encloses a 

 nuclear body having very little' chromatin other than the small cen- 

 trally located karyosome. Multiplication occurs only in the vegetative 

 state and by binary fission. 



Cyst Formation. Cysts are rarely observed, and then in small num- 

 bers ; the cyst wall is not heavy, but may show a double contour ; the 

 protoplasm is clear, free from all inclusions and vacuoles and shows a 

 single small nucleus, but without any signs of multiplication. It is 

 apparent, therefore, that the cyst is a, protective stage and has nothing 

 to do with reproduction, which occurs in the vegetative state only. In 

 this respect it resembles the Va*hlkampfia. 



Although the organism is almost constantly present in pyorrhea 

 alveolaris it is also found in healthy mouths, and in the absence of all 

 experimental proof, it is doubtful if the organism is of pathological 

 importance. Emetin has a decided effect upon many cases of pyorrhea 

 alveolaris, and under that treatment alone the disease may disappear ; 

 the nature of its therapeutic action is not yet clear, and does not neces- 

 sarily indicate any etiological relationship. 



