258 



THE PROTOZOA 



ENCYSTED STAGE 

 A. Entamceba histolytica 



B. Entamoeba coli 



1. Cyst smaller. 



2. Cyst less refractive. 



3. Cyst usually contains elongated re- 

 fractive bodies known as "chromidial 

 bodies." 



4. Nuclei never more than four. 



5. Cyst wall thinner. 



1. Cyst larger. 



2. Cyst more refractive. 



3. Cysts do not contain "chromidial 

 bodies." 



4. Nuclei eight, occasionally more. 



5. Cyst wall thicker. 



A method for bringing out the nuclear features is as follows: take a loopful of 

 2% acetic acid and a loopful of 2% formalin. Tinge the mixture to a rose color 

 with neutral red and then stir in a little saturated aqueous solution methyl green, 

 using a toothpick which has been dipped into the methyl green. 



In staining with iron haematoxylin or better with phosphotungstic haematoxylin 

 proper fixation is very important. Fix in 100 parts of sat. aq. sol. bichloride to 

 which is added 50 c.c. absolute alcohol and 5 drops glacial acetic acid. The stain 

 should be poured on the moist smear of faeces. The fixative should be heated to 

 6oC. and should only act for ten to twenty seconds. Then place in cold sub- 

 limate alcohol for ten minutes wash in 70% alcohol colored to a rich port wine 

 color with iodine, then in 70% alcohol, then in water and then stain as preferred. 

 Some like a carmine stain. The smears should be moist when fixed with bichloride 

 fixatives. A small loopful of Meyer's albumin fixative to emulsify is a great aid. 



AMCEB.E or PYORRHOEA ALVEOLARIS 



Recently much importance has been attached to certain amoebae 

 found deep in the pus pockets of affected teeth. They are best ob- 

 tained after wiping away the superficial pus and then scraping material 

 from the depths of the pockets with a wooden toothpick. They may 

 be emulsified in salt solution but saliva is better for the obtaining of 

 motility. The name is Entamceba gingivalis and it is probably the one 

 described under the names E. buccalis and E. dentalis. It rather re- 

 sembles E. histolytica in having a greenish refractile ectosarc and an 

 indistinct nucleus. Encysted forms have not been observed. 



It is open to question whether these amoebae are the cause or whether various 

 streptococci bring about the condition. A symbiotic relationship may be opera- 

 tive. Emetine seems often of value especially when combined with an autogenous 

 vaccine. The recent enthusiasm for emetine in treatment of pyorrhoea seems to be 

 disappearing. 



Entamceba gingivalis varies from 10 to 25/1 in diameter. The nucleus is much 

 smaller than those of the intestinal amoebae and has a distinct nuclear membrane en- 

 closing a deeply stained karysome. On the whole it is poor in chromatin, in this 

 respect rather resembling the histolytica nucleus. 



