GLAND-LIKE BODIEd IN THE BRTOZOA. 275 



The shape of the glands is subject to considerable change, no 

 doubt depending both on age and activity of function; but when 

 mature a constriction shows that they are divided into two parts, 

 the terminal portion having much larger cells than the portion 

 leading to the opercular opening. 



In 'Retepora cellidosa there are frequently two glands on each 

 side, as figured in my Supplementary ' Challenger ' Eeport, pi. iii. 

 fig. 13. The larger one seems to correspond with the glands in 

 other species, and the difference in appearance makes it all the 

 more difficult to understand what the function may be. 



These glands are now known in a considerable number of 

 species, for example in various MetejiorcB and Celleporce, Lepralia 

 JPaUasiana,Smift-ia nitida var. opMcliana, Smittia bispinosa, Smittia 

 trisjj/'nosa, Schizoporella sanguinea, and M.icroporella coriacea. 



Although thus occurring over a wide range, there are many 

 others in which I have not found anything of the kind, but we 

 should be alive to their sometimes having a somewhat different 

 appearance, as can be seen from Pi. XIX. fig. 16. 



In some zooecia o^ Smittia trispinosa the gland has much the 

 same form as in Scliizoporella sanguinea, whereas in others it 

 looks more like an oval or round body suspended by parenchym * 



* In normal conditions in the Bryozoa this parencliym tissue is composed of 

 a number of fine tlireads spreading tlirough the zooecia, buh in abnormal or 

 unhealthy conditions the appearance sometimes becomes more that of a solid 

 cord, and I take it that the figures given by Reichert and copied by Hincks 

 (Brit. Mar. Polyz. figs. xv. & xvii.) were taken from such specimens, for in Naples, 

 when I examined live and recent specimens of Zoohotryon pellucidum, the " colo- 

 nial nervous system " was always composed of numerous fine threads. These 

 threads constantly anastomose, and in the Chilostomata not only pass to the 

 neighbouring zooecia, but also to all the organs, as avicularia, ovicells, ovaria,and 

 testes. 



The lower part of the ctecum is almost surrounded by this plasma, and from 

 it numerous threads spread out. This has been described as a funicular platte, 

 but in the specimens examined it is not a solid structure. This accumulation of 

 plasma at the base of the ccecum suggests a simple explanation of the absorption 

 of nourishment into the colony, which is, that as the digestion principally takes 

 place in the c£ecum the plasma absorbs the results of digestion, and so by the 

 constant changes going on in the parenchym threads the digested nourishmen 

 is conveyed to all parts of the body. When a polypide is unable to obtain a 

 full supply of nourishment, the organic contents of the caecum being absorbed, 

 the portion remaining consists of the undigestible diatoms &c., and this soon 

 forms the brown body. The form of these parenchym threads is constantly 

 undergoing change through the whole of the zooecium. 



