310 MR. H. H. STIRRUP ON 



this corpuscle comes into contact with a strange fluid, such as 

 distilled water, the colourless body swells and begins to show 

 that it is really formed of a long thread of transparent substance. 

 This long thread is very much coiled, and as it swells out the rest 

 of the cell disintegrates. Text-fig. 64 shows three stages in the 

 disintegration of one of these coi-puscles. Salt solution is much 

 the best medium in which to examine the ccelomic corpuscles, as 

 they disappear very rapidly when put into distilled water. 



(c) The third type of corpuscle is the amoeboid corpuscle. 

 This is a small, almost spherical corpuscle, with a number of 

 clear pseudopodia. Text-fig. 65 shows a number of drawings 

 of the same amoeboid coi-puscle taken at intervals of about half a 

 minute. 



Text-fig. 65. 



pseud 



Drawings of the same amoeboid corpuscle ot M^Hchytraus pellucidus taken at 

 intervals of half a minute. 



Pseud., pseudopodia. 



In the living worm one often sees the free coelomic contents 

 moving apparently through the septa from segment to segment. 

 I often wondered whether there were any definite apertures in 

 the septa through which these corpuscles could travel, and, if so, 

 where they were. In transverse sections, I happened to get a 

 section through a septum which showed quite plainly that there 

 were at least two definite holes in the septum. These were 

 situated dorso-laterally and were semicircular in shape. They 

 were large and distinct, and the coelomic corpuscles were 

 especially crowded round the edges of the septum adjoining the 

 hole. 



Nephridia. — Goodrich (7) has given a full account of these 

 oroans in E. hortensis, a species closely allied to, if not identical 

 with, B. alhidtis, and I have been able to confirm his excellent 

 description in most particulars. 



There are no nephridia in the first six segments, the first 

 nephridium occurring in segment 7. The nephridium is a lobed 

 flattened body (PI. XLYII. fig. 13 a). It is composed of three 

 parts, an anteseptal portion, the flattened body of the nephridium, 



