SARCODINA 1067 



between twelve and twenty (Craig). Motility is well marked, though 

 it is not so active an organism as histolytica, the pseudopods, mostly 

 short and blunt, being formed of the clear, slightly refractile 

 ectoplasm. The endoplasm is granular, contains the nucleus and many 

 food vacuoles containing nuclei of leucocytes and granular matter, 

 and possibly a few red blood cells. Although Dobell and others main- 

 tain that red cells are never found. The nucleus is small, and in fresh 

 specimens is usually invisible. In structure, it is not unlike the 

 nuclei of coli and histolytica; the chromatin granules form a compact 

 and distinct ring obscuring the nuclear membrane. The karyosome 

 is small but distinct and is either central or slightly excentric and 

 is surrounded by a clear achromatic halo. There is no chromatin 

 visible between the karyosome and the nuclear margin. 



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 centrally located karyosome. Multiplication occurs only in 

 the vegetative state and by binary fission. 



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

 numbers ; 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 Vahlkampfia. The find- 

 ing of cysts is so rare that many investigators doubt their existence 

 altogether, and suggest that cysts when found may pertain to some 

 other organism accidentally present in the mouth. Further studies 

 are necessary. 



Transmission of the infection could occur directly by contact 

 from person to person by kissing, and a cyst stage is not, .therefore, 

 essential to the survival of the parasite. 



Although the organism is almost constantly present in pyorrhea 

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

 all experimental proof, it is doubtful if the organism is of patholog- 



