738 PROFESSOR J. STEPHKNSON ON 



ments are always to be observed, extending usually over the greater part or the whole 

 of the intestine. They are very regular in rhythm ; the frequency may be from 

 seventeen to thirty-six per minute. Matter in the intestine may at times be moved 

 for some distance in an anterior direction by the antiperistalsis ; or particles may be 

 seen to oscillate, moving anteriorly for a little distance with the antiperistaltic wave, 

 and seeming to recoil back again after it has passed, as if the pressure was now directed 

 backwards. FfBces nearing the anus may also be carried some distance back in their 

 course, i.e. anteriorly, by the combined antiperistalsis and reversed ciliary action. 



A direct (antero-posterior) peristalsis was observed in this species ; it was slower 

 than the usual antiperistaltic movements, and occurred for some distance both in front 

 of and behind the zone of budding in an animal which was preparing to divide. In 

 one portion of their extent the movements of the gut- wall were mainly confined to the 

 ventral side of the intestine. At the posterior limit of their extent, which was about 

 the junction of the anterior and middle thirds of the hinder of the two components into 

 which the animal was about to divide, they were quite overcome by the antiperistaltic 

 movements of the hinder portion of the intestine. 



The ascending ciliary action is well marked in this species, and may often be called 

 violent ; it may be very obvious with the low power. It begins at the anus, and ceases 

 when the anus is temporarily closed. Particles of Indian ink are swept towards the 

 anus from some little distance outside, and enter the aperture ; they ascend some way 

 up the intestine, but cannot be followed far. 



Branchiodrilus hortensis (Stephenson). 



In this species (48), which belongs to one of the few genera of Oligochfeta which 

 possess gills, antiperistalsis is well marked and of general occurrence. The frequency of 

 the waves may vary from seven to twenty -four per minute ; they may be very violent, 

 and may extend through the whole length of the intestine, i-eaching as far as the hinder 

 end of the oesophagus. In some specimens the contractions were numerous, distinct, 

 and well detiued, but embracing only a small longitudinal extent of the gut-wall ; the 

 appearance was therefore that of a series of ring-like constrictions of the gut, and since 

 these travelled slowly along, seven to nine separate constrictions could be seen in the 

 low-power field of the microscope at once. On one such occasion their character changed 

 while under observation ; they became larger and less numerous, so that only two were 

 in the field at the same time. 



Ascending ciliary action does not always occur, the anus being frequently kept 

 closed ; it may, however, be violent and easily visible with the low power. 



Aulophorus tonkinensis (Vejd.). 



This species, first described by Vejdovsky from an incomplete specimen, has more 

 recently been investigated by Michaelsen (33) and myself (49). The ojjportunity of 



