358 



EVENINGS AT THE MICROSCOPE. 



tached from the animal, thus proving that the moving power, 

 whatever it is, is situated in the constituent tissue itself. 



Under pressure the edges of the flattened acontium 

 appear to be thronged with clear viscous globules, over- 

 lapping one another, and protruding; indicating one or 

 more layers of superficial cells, doubtless forming the 

 epithelium.* As the pressure is increased, these ooze 

 out as long pear-shaped drops, and immediately assume a 

 perfectly globular form, with a highly refractive power. 

 Below these are packed a dense crowd of cnida, arranged 

 transversely. 



Before we proceed to the examination of these curious 

 organs in detail, it may be well to devote a moment's 

 attention to the mechanism by 

 which the acontia themselves 

 are projected from the body. 

 As this was first described (so 

 far as I am aware) by myself,! 

 I will take the liberty of citing 

 some of my observations on 

 the matter. 



The omission of the acon- 

 tia is provided for by the exist- 

 ence of special orifices, which 

 I term cinclides. The integu- 

 ment of the body, in the Sagar- 

 tia, is perforated by minute 

 foramina, having a resemblance 

 in appearance to the spiracula 

 of Insects. They occur in the 

 interseptal spaces ; opening a 

 communication between these 



CINCLIDES. 



* The thin, delicate cuticle or skin which covers all the free, un- 

 inclosed, internal surfaces of the body. 



f In a memoir, entitled " Researches on the Poison Apparatus in the 

 Actiniadze," read before the Royal Society, Feb. 4th, 1858. 



