116 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
end of the section (the section being of the form 
represented by A B in the figure). These relations, 
as we have seen, are the more favourable to correct 
localization: (a) the greater the radial distance be- 
tween the point of stimulation and the end of the 
section ; and (b) the less the circumferential distance 
between the point of the stimulation and the radius 
let fall from the end of the section. But we have 
seen that the limits as regards severity of section 
within which these gradations of localizing ability 
occur, are exceedingly restricted—a cut of only a 
few millims. in length, even though situated at the 
greatest radial distance possible, being sufficient to 
destroy all localizing power of the manubrium as 
regards the middle point of the corresponding are 
of the margin, and a stimulus applied only a 
few millims. from the attached end of a severed 
marginal strip entirely failing to cause localizing 
action of the manubrium. Lastly, we have seen 
that even after all localizing action of the manu- 
brium has been completely destroyed by section of 
the kinds described, this organ nevertheless con- 
tinues actively, though ineffectually, to search for 
the seat of irritation. 
The last-mentioned fact shows that after excita- 
tional continuity of a higher order has been 
destroyed, excitational continuity of a lower order 
nevertheless persists; or, to state the case in 
other words, the fact in question shows that after 
severance of the almost exclusively radial connec- 
tions between the bell and the manubrium, by 
which the perfect or unimpaired localizing function 
