HETEROKA R YO TA 



four micro- and four macro-nuclei are in the same cell, which divides 

 into two very small cells with two macro- and micro-nuclei each. 

 These cells grow to nearly full size, and then divide, giving rise to 

 the typical protozoon, with one macronucleus and one micronucleus. 



Parasitism. — great many species of the Ciliata are parasitic in 

 the intestine or bladder of other animals, and some are epizoic. 



The latter will often be met with as VorticellcB, living on Anopheles 

 and Culex larvae. The former are found largely in the Orthoptera, 

 the Amphibia, and in herbivorous mammals — -e.g., horse and cow. 



In man a few have been recorded: Chilodon dentatus Dujardin, 

 1842; C. uncinatus, Colpoda cucullus Schutz, 1889; Balantidium coU 

 Malmsten, 1857; ^- w^"^^^^^ Jakobi and Schaudinn, 1898; Nycto- 

 thevusfaha Jakobi and Schaudinn, 1898; A^. giganteus Krause, 1906; 

 N. africanus Castellani, 1905. 



Parasitism does not appear to affect the structure of the animal, 

 unless the loss of the cytostome in Opalina, parasitic in frogs, is 

 considered to be due to this cause. 



Pathogenicity. — The ciliate parasites, as a rule, appear to cause 

 but little effect, unless they are present in large numbers, when 

 diarrhoea, often severe and long-persisting, may result. 



Classification. — -The Ciliata are classified into four orders: — 



Order /. Holotricha Stein, 1859. — Mobile Ciliata without special 

 oral cirri (Chilodon, Colpoda). 



Order II, Heterotricha Stein, 1859. — Mobile Ciliata with special 

 oral cirri (Balantidium, Nyctotherus). 



Order III. Hypofricha Stein, 1859. — -Mobile Ciliata, with well- 

 developed dorsal and ventral surfaces. Not known to be parasitic 

 in man. 



Order IV. Peritricha Stein, 1859. — Fixed Ciliata. Not known to 

 be parasitic in man. 



ORDER I. HOLOTRICHA Stein, 1859. 



Definition. — ^The Holotricha are free-moving Ciliata, in which 

 all the cilia are of approximately equal length and thickness, and 

 never possessing cirri. 



Remarks. — It is divided into two suborders : — 



Suborder i, Gymnostomata.- — Mouth closed when ingesting food. 



Suborder 2, Hymenostomata.—yioMth. always open, and provided 

 with an undulating membrane. 



SUBORDER GYMNOSTOMATA Biitschli, 1889 

 Family Chlamydodontid^ Stein.- — -In this family there is a 

 genus Chilodon Ehrenberg, 1833, which includes oval, strongly dorso- 

 ventrally compressed Chlamydodontidse, commonly found in 

 infusions, of which one species, C. dentatus Dujardin, 1842, was 

 found in great abundance by Guiart in the motions of a woman 

 suffering from severe dysentery in Paris. Manson and Sambon 

 have described a case of chance-parasitism due to another species, 

 C. uncinatus Blochmann, in a patient from tropical South Africa. 



