PROTOZOA AND OTHER ANIMALS 905 



Playfair (1921), who made his studies in the vicinity of Sydney also, 

 stated that on one occasion he found half a dozen specimens of Aitasia 

 }77aygaritijera Schmarda within the tissues of a turbellarian. This species 

 he also found in the water of ponds, not in a free-swimming form and 

 very often lacking a flagellum. This is the only species of Astasia that he 

 reported in the survey of Australian fresh-water flagellates, and his iden- 

 tification is not convincing proof that the form in Turbellaria is the 

 fresh-water species named. 



Astasia captiva was described by Beauchamp (1911) from the rhabdo- 

 coele Catenula lemnae in France. In one pond almost all individuals were 

 infected, while in another a mile away the flagellates occurred in a small 

 percentage only. In some there were only one or two to a chain of 2o6ids, 

 whereas in others the flagellates were very abundant. They were in con- 

 tinual movement in the "pseudocoele," between the parietal cells. A 

 flagellum was present sometimes even on flagellates in the tissue, but 

 most of the organisms lacked that structure. A colorless rudiment of a 

 stigma, which was invisible in life, was seen frequently in stained prep- 

 arations. Beauchamp stated that no euglenid was seen in other species 

 of rhabdocoeles, including the common Stenostomwn leucops. Howland 

 (1928) identified as Astasia captiva an actively metabolic euglenoid 

 flagellate, without flagellum or stigma, which she observed in Stentor 

 coeruleus and Spirostomum amhigimm. 



S. R. Hall (1931) found euglenids rarely in the mesenchyme of an- 

 other species of Stenostomum and in S. predatorium in Virginia, where 

 Kepner and Carter (1931) doubted the existence of 5. leucops. While 

 the flagellate was in the host, the flagellum did not extend beyond the 

 edge of the body; but when it was liberated into water the flagellum 

 soon grew out, metabolic movement ceased, and the organism swam 

 rapidly. The euglenids could be kept alive in spring water for three or 

 four days, but attempts to cultivate them failed. When infected hosts 

 were added to a culture of the rhabdocoeles, practically all became in- 

 fected within a week. In one instance, when an infected worm was de- 

 voured by another, several flagellates were observed to pass through the 

 wall of the enteron into the mesenchyme, where they multiplied. There 

 was no apparent effect on the host except in instances in which two or 

 three hundred were present; then the rhabdocoeles became sluggish and 

 bloated, ruptured with liberation of the flagellates, and died. 



