HYDROID ZOOPHYTES. 59 



It seems not yet to be ascertained what is the nature of 

 these excrescences; what functions they perform, or what 

 relation they sustain with the polypi, or their house. In 

 truth, from the fact of not all the cells being provided 

 with them, and of other polypidoms having generic cha- 

 racters in common with this species, showing no signs of 

 possessing or requiring these excrescences, a doubt is justly 

 suggested, whether they may not, after all, be independent 

 and distinct, although parasitic organisms, consisting of 

 what would look like an animal, all head and mouth, 

 swaying to and fro, snapping its jaws and seeking what 

 it may devour. On the other hand, its occupation may be 

 that of a useful member of the polypidom, auxiliary to the 

 seizure and imprisonment of wandering animalcules for the 

 purpose of feeding the polype in its cell. 



All these interesting forms, to be appreciated, require 

 the most careful observation by means of the microscope, 

 with the objects in a living state. The day for dried 

 specimens has now gone by, and it may soon be a common 

 every-day amusement to examine this class of Zoophytes in 

 glass vessels, and trace their admirable structures in the 

 same manner in which only the Ellises, the Johnstons, and 

 the Gosses have hitherto been privileged to do. 



