ON POLYPS. 



rived from it. Between the digestive sac c, and the fibrous ex- 

 terior of the body a, is a considerable space d, divided by a great 

 number of perpendicular fibrous partitions, /, into numerous com- 

 partments, which however communicate freely with each other, and 

 likewise with the interior of the tentacula, as seen at e. Every 

 tentacle is perforated at its extremity by a minute aperture , 

 through which the sea-water is freely admitted into these compart- 

 ments, so as to bathe the interior of the body ; and when from 

 alarm the animal contracts itself, the water so admitted is forcibly 

 expelled in fine jets through the holes by which it entered. There 

 can be no doubt that the surrounding fluid, thus copiously taken 

 into the body, is the medium by which respiration is effected ; and 

 every one who has been in the habit of keeping Actiniae in glass 

 vessels for the purpose of watching their proceedings, must have 

 noticed that as the fluid in which they are confined becomes less 

 respirable, from the deficiency of air, the quantity taken into the 

 body is enormous, stretching the animal until it rather resembles 

 an inflated bladder than its original shape. 



(59.) It is in the compartments which are thus at the will of the 

 creature distended with water, that we find the organs of reproduc- 

 tion, which here assume a developement far exceeding what we have 

 noticed in other zoophytes. On raising a portion of the mem- 

 brane which forms the stomach, as aty, we see lodged in each par- 

 tition an immense number of ova attached to a delicate transparent 

 membrane, and arranged in large clusters, g. The ovigerous mem- 

 brane which secretes these eggs is represented unravelled at h ; it is 

 through its whole extent bathed with water admitted into the compart- 

 ment in which it is lodged, a circumstance which provides for the re- 

 spiration of the ova during their developement. The convoluted ovary 

 is seen to terminate by a minute aperture near the bottom of the sto- 

 mach k, into which when mature the young escape. The eggs found in 

 the ovaria are round and of a yellow colour, resembling minute grains 

 of sand : it is probable that sometimes they are hatched after their ex- 

 pulsion, but it is likewise asserted by numerous authorities that the 

 young are not unfrequently born alive. The manner in which the 

 ova are extruded has been long a matter of controversy, and perhaps 

 cannot yet be regarded as definitively ascertained. Our own dissec- 

 tions would lead us to concur with those anatomists who describe 

 them as escaping from the ovaria into the bottom of the stomach, 

 whence they have been seen to escape by the mouth fully formed : 

 it is possible, however, that they may likewise be expelled with the 



