800 PKOFESSOR J. STEPHENSON ON 



Spionid^. 



The only observation that I have to record for this family refers to Nerine vulgaris. 

 Antiperistalsis was present ; but there was no relation between the contractions of the 

 dorsal vessel and those of the intestine. 



CH/ETOPTERID^. 



Chsetopterus variopedatus. 



This animal is of some size, and the interior of the alimentary canal cannot be 

 observed with either a dissecting or an ordinary microscope ; hence the examination 

 presents a certain amount of difficulty. The following methods were adopted : — 



A specimen was placed on a glass plate and the posterior end covered with an 

 ordinary glass slide. The compression was sufficient to flatten the hinder part of the 

 animal fairly well ; and the very end of the alimentary canal was then transparent 

 enough to allow a violent ascending ciliary motion to be seen with the dissecting 

 microscope. Around and outside the anus, ciliary motion is obvious and violent, at 

 times apparently not acting in any definite direction, at others working towards the 

 alimentary canal. 



Carmine in suspension was now run under the covering slide. This, or the pro- 

 longed experimentation, occasioned a considerable discharge of mucus, which caused 

 the carmine to aggregate into small flocculi. A slow current towards the end of the 

 intestine, beginning some little distance away, and gradually increasing in swiftness as 

 it approached the anus, was thus made visible. Some of the carmine accumulated in 

 small masses round the anus ; but the large majority of smaller particles were carried 

 with some violence into the intestine, while a few were possibly deflected and helped to 

 swell the flocculi near the margins of the orifice. 



The specimen was now placed for 25 minutes in a dish containing water 

 with carmine in suspension, and afterwards again examined. A fair-sized flocculus of 

 carmine particles was now seen to be hanging out of the anus ; this had probably been 

 forced out of the intestine by the manipulations necessary in moving the animal. This 

 flocculus was slowly drawn into the intestine while the animal remained under observa- 

 tion. Fresh carmine added formed flocculi with the mucus excreted from the surface 

 of the body, and those flocculi which came in contact with the lobes round the anus 

 were slowly drawn over them and through the margins of the anus into the intestine. 

 Smaller particles were also drawn in, but notably the larger ones, and small flocculi, 

 as described. 



The question suggested itself whether the mucus might not normally have the 

 function of entangling particles to be subsequently ingested by the anus. But it is 

 hardly likely that this is a principal object of its secretion, since it is formed over the 

 whole surface of the body. 



No antiperistaltic contractions were observed. 



