FUNDAMENTAL EXPERIMENTS. al 
amount of section it is possible to make upon any 
of their parts other than their margins without 
their spontaneity being in the smallest degree 
affected. 
Effects of excising Certain Portions of the Llargins 
of Nectocalyces. 
The next question which naturally presents itself 
is as to whether the locomotor centres are equally 
distributed all round the margin of a swimming 
organ, or situated only, or chiefly, in the so-called 
marginal bodies. To take the case of the naked- 
eyed Meduse first, it is evident that in most of the 
genera, in consequence of the intertentacular spaces 
being so small, it is impossible to cut out the 
marginal bodies (which are situated at the bases of 
the tentacles) without at the same time cutting out 
the intervening portions of the margin. The genus 
Sarsia, however, is admirably adapted (as a glance 
at Fig. 1 will show) for trying the effects of remov- 
ing the marginal bodies without injuring the rest 
of the margin, and vice versd. The results of such 
experiments upon members of this genus are as 
follow. 
Whatever be the condition of the individual 
operated upon as to freshness, vigour, etc.,it endures 
excision of three of its marginal bodies without 
suffering any apparent detriment; but in most 
cases, as soon as the last marginal body is cut out, 
the animal falls to the bottom of the water quite 
motionless, If the subject of the experiment 
