CRAIG I A 



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called a * Nebenkoerper.' Reproduction was by simple fission and by cyst 

 formation, in which the parasite broke up into a number of spores, each of 

 which contained a piece of the nucleus and a piece of the Nebenkoerper. Each 

 of these spores develops two flagella, and breaking out of the cyst forms the 

 swarm stage. Finally the flagella are lost, after longitudinal division, and the 

 spores become small amoebae. 



In 1906 Craig found a parasite resembling that described by Schaudinn 

 in the faeces of patients suffering from chronic dysentery in the Philippine 

 Islands. He considered that they were the pathogenic agent of the symptoms 

 from which the patients suffered, and because of their similarity to Schaudinn's 

 organism called them Paramceba hominis Craig, 1906, and as such we described 

 them in the first two editions of this work. 



In 1912 Calkins considered that Craig's parasite could not be classified in 

 the genus Paramceba, because its swarm spores have only one and not two 

 flagella, while its extranuclear body is apparently ditierent from that in 

 Paramceba. He therefore gave it the name Craigia hominis (Craig, 1906), 

 which Jepps and Dobell consider a non-existent organism and the genus a 

 nomen nudum. 



In 1915 Barlow discovered a new species, which he called Craigia migrans 

 in Honduras. 



Craig thinks that probably infections with this parasite are widespread, 

 and that they may be often confounded with Cercomonads, etc. 



Species. — There are four known species — viz., two parasitic in marine worms 

 and two parasitic in man. The latter are distinguished as follows : — ■ 



A. Small accessory extranuclear body present in larger forms. Flagellate 



forms multiply by longitudinal division — Hominis. 



B. Small accessory extranuclear body absent. Flagellate forms do not 



divid e — Migrans . 



Craigia hominis Craig, 1906. 

 Synonym. — Paramceba hominis Craig, 1906. 



Definition. — Craigia in which the accessory nuclear body is present in the 

 larger forms, and the swarm spores divide longitudinally, the accessory body 

 and the motile organ participating in this division. 



History. — It was discovered in 1906 by Craig, in the Philippine Islands, in 

 cases of chronic diarrhoea, and in 191 5 by Barlow, in Honduras, where it not 

 only causes a form of chronic diarrhoea, but also severe ulcerative conditions 

 of the intestine, resembhng those of amoebic dysentery. Barlow fully con- 

 firmed Craig's observations. 



Morphology. — In the amosba stage it measures from 15-25 microns, and 

 possesses an ectoplasm which is clearly visible during motion, but not while 

 at rest. The endoplasm is granular, and contains a nucleus which is distinct 

 and composed almost entirely of chromatin. There is also an extranuclear 

 body which is of an accessory nature. 



Life-History. — The amoeba can reproduce by binary division for some time, 

 at the end of which it encysts, surrounding itself with a double contoured 

 envelope, and divides into a number of small, spherical bodies, each of which 

 contains a piece of the nucleus and a portion of the accessory body. The cyst 

 now ruptures and the spores escape as uniflagellate swarm spores, some 3-20 

 microns in length. This is the flagellate stage. These little pear-shaped 

 flagellates divide by longitudinal fission, in which the accessory body and the 

 flagellum take part. Later the flagellates cease to move, lose their flagella, 

 and become amoebae, thus completing the cycle of the life-history. 



Cultivation. — We are not aware of any attempts at artificial cultivation. 



Pathogenicity. — It causes chi-onic diarrhoea and dysentery in man. 



Craigia migrans Barlow, 191 5. 

 Definition. — Craigia in which the accessory nuclear body is absent, and in 

 which the swarm spores do not divide longitudinally before becoming amoebae. 

 History. — It was discovered by Barlow in fifty-one infections in Honduras, 



