Nervous System of Actinia. 273 



the tentacle, and beneath a corresponding layer, or one of bacilli, in the 

 peristome. I have failed to recognize any nervous elements in the 

 tentacles save the fusiform bodies, and there are none in the peristome 

 except these irregular cells. 



Again, the Hainiean bodies are found in the chromatophores, in some 

 places, amidst the Eotteken bodies, separating them. 



Nevertheless it is true that light falling on the surface of an Actinia 

 will reach further into its structures where there are Haimean bodies, 

 and further still if the Eotteken cells underlie them. Where there is 

 no pigment intervening between the bodies when placed side by side, or 

 between the Eotteken cells, a diffused glare of light would impinge on 

 the granulo-cellular layer below them, in which the nerves ramify and 

 the nerve-cells exist. But when the pigment-granules and cells exist, 

 they break up the general illumination and confine it to a series of 

 separate bright rays. Each of them is brighter than the corresponding 

 space of diffused light ; and it would appear that the bacilli, the Haimean 

 bodies, and the Eotteken cells in combination, concentrate light. 



Two or three bacilli are placed side by side and behind each other over a 

 small Haimean refractile spherical cell, and perhaps tw'enty or more cover a 

 large cell (PL II. fig. 15). Usually a Haimean body is placed immediately 

 over a Eotteken body ; but, as Eotteken has pointed out, this is not an 

 invariable arrangement, for some cover the spaces between and over 

 them. The refractibility of the fluid contents of the Haimean bodies 

 and Eotteken cells appears to be the same ; but the elongated form of the 

 last-mentioned structures may act upon light as if their internal fluid 

 were more viscid. 



In every instance there is a more or less opaque tissue between the 

 proximal end of the Eotteken body and the nerve-cells ; and, moreover, 

 the delicate protoplasmic layer, which is slightly impervious to light, 

 surrounds the Haimean bodies. 



In my opinion the Haimean bodies, wherever they exist, carry light 

 more deeply into the tissues than the ordinary epithelial structures. 

 This is also the case with the bacilli and Eotteken bodies, even when they 

 exist separately and with or without the Haimean bodies. There are 

 three ordinary constituents of the skin, and through their individual gifts 

 and structural peculiarity they place the Actinia in relation with light. 

 "When they are brought together in this primitive form of eye, they con- 

 centrate and convey light with greater power, so as to enable it to act 

 more generally on the nervous system probably not to enable the 

 distinction of objects, but to cause the light to stimulate a rudimentary 

 nervous system to act in a reflex manner on the muscular system, which 

 is highly developed. The Actinia, therefore, may feel the light by means 

 of the transparent histological elements when they are separate and 

 constitute integral portions of the ectoderm j but this sensation will be in- 



