MR. E. R. LANKESTER ON SOME LOWKR ANNELIDS. C>37 



face of the pharynx and join to form a single ventral vessel close to the bulb of the 

 pharynx. Here, too, almost at once, are given off the two hi lily dilatable lateral \ esseh 

 The ventral vessel is non-contractile and is not adherent to the wall of tin- intestine nee 

 figs. 12-14). 



The dorsal vessel does lie closely on the intestine -wall, and becomes covered in part-, 

 as do its main branches, with aggregations of minute browiuMi granules. The a ssels 



of the tegumentary or respiratory system of course meet the great trunks and the intes- 

 tinal system at either end of the worm, and are, it is to be suppled, elsewhere connected 

 by branches from the dorsal and ventral trunks. Parallel \« sols passing transversely 

 almost round the worm are arranged at close intervals, and connected by the finest 



The 



interweaving capillaries (fig. 23). This constitutes the respiratory systom 

 weaving capillaries are perhaps rather lacunar spaces in the tissue than capillaries uitl 

 walls, but seem eminently adapted, from their position and structure, to facil 

 free interchange of the gases of the vascular fluid and surrounding water. 



i 



i 



ever, express a doubt (which I cannot clear up) H to whether these apparent vessels may 

 not be simply furrows or thickenings of the integument. 



Perivisceral Cavity and Fluid.- -The space between the alimentary tul.o and the bod} 

 wall in Chcetogaster limntei is larger proportionally than in the Lnmbru ids, but 

 not so ereat as in JBolosema. It is traversed by numerous muscular bundle - tit " 



tl 



pharynx ; and a few pass to the stomach-one apparently septal muscle extendm across 

 it at "the anterior end of the stomach, and another at the posterior const r..-t ion dmdin 

 stomach from intestine, and perhaps another for each succeeding pan- of bnstie-bnndl 

 It contains, of course, a fluid, in which float granules and cells, and in which an 



suspended the segment-organs. The granules and cells vary to a very great deg. 

 number ; in some individuals there are hardly any, in others the cav.tv Ken. packed 

 them. There is a very distinct relation between the abundance JMJ-_£^ 



granules and cells and the abundance of the browmsh granule, which 



masses the dorsal vessel and its ramifications on the stomach or m est 



in 



Clai 



his 



Recherches sur les Oligoehetes,' has spoken of the browns-How • h 



of the intestine in Lumb 



ontinued to and surrounding the dorsal ve* 1, 

 re intestine in jjumurtw .^"-a -uum ™vivUrvr»l rolls 



- ^ ^ <« «* tT'i"- ™ir«r::;:::, ' : s» i - 



nected the two. It 



have but little to do with the 



etion of digestive juices, or, at any 



have but little to do witn tne «*-"-». ?~~ * duction f the corpuscles of 



additional and most important connexion wtth the pi -od^onol J* 



ith the liquid of 





When I have found the per 



masses of granules adhering to the dorsal vessel and to 



01 granules auuci^ *» , ^^Hr (t\ 



two such masses floating alone in the perivisceral cm J 



-er orouwix. *, v* sometime 



On the ot lie 



the vessels of 



hand, when the cavity lias been full of corpuscles »g aoimueta .und ill the 



tine have been almost entirely free ^J™*?! j, differcnt individuals. There 



perivisceral fluid differ not only in number, but in kind, 



