On Trichoclina as an Endoparasite. By T. B. Rosseter. 931 



opaque object, and afterwards immersed in sterilized water and 

 teased out with needles. The result was to confirm my previously 

 formed opinion, that the animals were not endoparasitic in these 

 organs. 



The alimentary canal was next detached its whole length, with 

 a portion of the mesentery ; the latter was spread out and examined 

 with 1 in. and 1/2 in. objectives, but no signs of parasitic life were 

 visible. The alimentary canal was also examined externally its 

 whole length, and then placed in a perfectly clean trough with 

 some of the distilled water. The intestine was very much attenu- 

 ated, due to the fact that my stock had been kept short of food for 

 a few days. It was then opened its whole length, and examined 

 in sections. The cloaca was carefully examined, as the ureters 

 and the urino-seminal duct (plate XVIII. fig. 1,/and g) terminate 

 in a short canal, at the back of the cloaca. Not a specimen of 

 Tricliodina was, however, found either within the alimentary 

 canal or in the fluid in which it was immersed. 



I next examined the testes and renal organs and their ducts. 

 These were extracted, spread out on a glass plate under a lens, 

 distilled water added, and examined by a 1 in. objective. The 

 testes were tolerably free, an occasional Tricliodina being seen in 

 their neighbourhood and among the efferent ducts. But it was 

 otherwise with the renal organs; the fluid in their immediate 

 neighbourhood was literally alive with the Tricliodina, which 

 swarmed over the kidneys and amongst the ureters, at times 

 detaching themselves and moving about, and then settling them- 

 selves down and twirling round and round with a concentric motion. 

 Here, then, amongst the urino-seminiferous organs, was the habitat 

 of these ecto-endo- Tricliodina, a locality which, up to the present 

 time, according to the authorities with which I am acquainted, had 

 escaped the notice of old and recent investigators, the Tricliodina 

 being looked upon as purely ectoparasitic and free-swimming in 

 their habits. 



Having established the habitat of the organisms, I endeavoured 

 to ascertain their relationship to the parasites of the Hydra. 



Hydras from a pond (known as the "reed-pond") were ex- 

 amined, and found free from Trichodina pediculus ; larvas of Triton 

 cristatus were taken from another pond at some distance, and 

 specimens of Tricliodina were detached from the branchias, taken 

 up with a pipette, and placed with the Hydras in a watchglass, a 

 small quantity of water being added. Specimens of Tricliodina 

 were then taken from a newly dissected newt, put into a watch- 

 glass with a small quantity of water, and one of the Hydras added. 

 The former was used as a control experiment, and attention was 

 specially directed to the latter. 



When placed in the watchglass the Hydra was of course con- 



3 p 2 



