xiii, b, 6 Haughwout: Flagellated and Ciliated Protozoa 223 



one of which is directed forward and the other downward and 

 backward in heteromastigote fashion. There is a principal 

 nucleus (trophonucleus ?) , and there is another body of supposed 

 nuclear nature that has been variously termed the kinetonucleus, 

 or the blepharoplast. Absolute proof of the parasitic nature 

 of this organism is still lacking, and there is a tendency to re- 

 gard it as a free-living form, which has contaminated stools or 

 urine. I have never seen it in pond or tap water, but some 

 observers have reported it as occurring free. 3 



To my mind there is some ground for suspecting that Protri- 

 chomonas, Trichomastix, Macrostoma, and possibly Cercomonas 

 may represent developmental stages in the life cycle of Tricho- 

 monas, and Minchin(35) suggests that as Trichomonas and Tri- 

 chomastix frequently occur in the same host they are "perhaps 

 to be interpreted as two developmental phases of the same or- 

 ganism rather than as distinct generic types." 



Reproduction in Trichomonas has been described by several 

 writers as taking the form of simple longitudinal binary fission, 

 which may, at times, give way to multiple fission. Recent inves- 

 tigations seem to indicate that either form of reproduction may 

 occur. Cyst formation is unproved, many writers doubting if it 

 occurs. 



Woodcock (52) considers that Trichomonas may have lost the 

 power to produce cysts and considers it likely that "infection 

 with trichomonas can take place by means of the active, un- 

 encysted forms." (The italics are Woodcock's.) He found that 

 Trichomonas would live and remain active for five and one-half 

 hours, both in 0.066 hydrochloric acid solution and also in pan- 

 created solution of a strength that would bring about the excys- 

 tation of Entamoeba histolytica. 



In this connection Wenyon(50) states that the rounded-out 

 forms are capable of resisting the action of gastric juice for 

 a considerable time, which might, as Woodcock says, account for 

 the safe passage of the naked parasites through the stomach. 

 The bodies appearing in the faeces of man and of some of the 

 lower animals and generally spoken of as Blastocystis enter- 

 ocola or Blastocystis hominis have been thought by many to be 



3 Macfie (Journ. Trop. Med. & Hyg. (1917), 20, 1), reporting from 

 Accra, states that flagellates soon make their appearance in bottles of 

 saline solution or distilled water exposed in the laboratory. Apparently 

 the organisms develop in the thin layer of fluid between the neck of the 

 bottle and the ground glass stopper. They are not usually found in the 

 fluids inside the bottles. These flagellates appeared to belong to the genus 

 P rowazekia of Hartmann and Chagas. 



