SECTION OF NAKED-EYED MEDUSZ&. 111 
at least, to the size which is compatible with con- 
ducting these experiments—is independently en- 
dowed with the capacity of very precisely localizing 
a point of irritation which is seated either in its 
own substance or in that of the bell. 
We have here, then, a curious fact, and one 
which it will be well to bear in mind during our 
subsequent endeavours to frame some sort of a con- 
ception regarding the nature of these primitive 
nervous tissues. The localizing function, which is 
so very efficiently performed by the manubrium of 
this Medusa, and which if anything resembling it 
occurred in the higher animals would certainly 
have definite ganglionic centres for its structural 
co-relative, is here shared equally by every part of 
the exceedingly tenuous contractile tissue that 
forms the outer surface of the organ. I am not 
aware that such a diffusion of ganglionic function 
has as yet been actually proved to occur in the 
animal kingdom, but I can scarcely doubt that 
future investigation will show such a state of things 
to be of common occurrence among the lower 
members of that kingdom.* 
* The only case I know which rests on direct observation, and 
which is at all parallel to the one above described, is the case of 
the tentacles of Drosera. Mr. Darwin found, when he cnt off the 
apical gland of one of these tentacles, together with a small por- 
tion of the apex, that the tentacle thus mutilated would no longer 
respond to stimuli applied directly to itself. Thus far the case 
differs from that of the manubrium of Tiaropsis indicans, and, in 
respect of localization of co-ordinating function, resembles that 
of ganglionic action. But Mr. Darwin also found that such a 
“headless tentacle ” continued to be influenced by stimuli applied 
to the glands of neighbouring tentacles—the headless one in that 
