INTESTINAL RESPIRATION IN ANNELIDS. 737 



Oligochseta. The appearances are, however, very obvious, and must be familiar to all 

 students of the group ; it is surprising, therefore, that they should hitherto have received 

 so little notice. Hence it appears useful to call attention to them, and to what they 

 imply, viz. that the intestine in the aquatic Oligochgeta has a respiratory function. 



I have already made brief mention of the occurrence of antiperistalis and ascending 

 ciliary action, in the anatomical descriptions of certain aquatic Oligochasta of the Punjab 

 (46, 47). I have since then continued and extended my previous observations, both 

 in India and at Millport in Scotland, with results which are set forth in what follows. 



Naidid^. 



Nais com7nunis Piguet, var. punjahensis. 



The above (47, 48a), which I at first supposed to be a variety of N. variabilis 

 Piguet, is one of the commonest of the aquatic Oligochseta of Lahore ; and it is one 

 in which the antiperistaltic movements may be seen almost constantly. 



Such movements usually occur fairly regularly at intervals of a few seconds. They 

 extend forwards for a considerable distance, often as far as the stomach, i.e. to about 

 the eighth segment. In kn animal which is about to divide by fission into two, the 

 zone of budding off'ers a certain resistance to the forward passage of the wave ; the 

 antiperistaltic waves, having traversed the whole length of the posterior animal, are 

 momentarily checked at this point, and, if feeble, fail to enter the anterior animal ; 

 or, in other cases, only the more violent of the series pass forward beyond this point. 

 Occasionally the antiperistalsis is replaced by a direct, or antero-posterior peristalsis 

 at the hinder end of the animal ; this occurred on one occasion after the animal had 

 been under observation for some time in a small quantity of water ; one may recall 

 the fact that in the higher animals the second stage of asphyxia is characterised by 

 violent expiratory movements. 



The ascending ciliary movement is not invariably to be seen, and its presence or 

 absence is often dependent on the opening or closure of the anus. In the same 

 specimen the anus may at first be open and ciliary motion well marked, while later 

 the anus is closed and ciliary motion stops. The presence of large quantities of food 

 or faecal matter in the intestine is not a hindrance to ciliary action ; this may be 

 very well marked all along the sides of such masses, though they may almost fill 

 the lumen. 



Slavina punjahensis Stephenson. 



The species of the genus Slavina are usually found coated with a layer of foreign 

 matter, which renders the examination of their minute anatomy difiicult, or in some 

 specimens impossible. The present species (47) forms no exception to the rule, but 

 the hinder part of the body is frequently less opaque than the anterior, and in suitable 

 specimens it is not difficult to establish the following points : — Antiperistaltic move- 



