SECTION OF NAKED-EYED MEDUSZ. 125 
the usual response to muscular irritation being an 
ordinary locomotor contraction, which forms a 
marked contrast to the tonic spasm that znvariably 
ensues upon stimulation of the margin, and almost 
invariably upon the stimulation of a radial tube. 
The first question I undertook to answer was the 
amount of section which the excitable tissues of 
Staurophora laciniata would endure without losing 
their power of conducting the spasmodic contraction 
from one of their parts to another. This was a 
very interesting question to settle, because Stauro- 
phora laciniata, like all the other species of disco- 
phorus naked-eyed Meduse, differs from Aurelia, 
etc., in that the ordinary contraction-waves are very 
easily blocked by section. It therefore became in- 
teresting to ascertain whether or not the wave of 
spasm admitted of being blocked as easily. First, 
then, as regards the margin. [f this be all cut off in 
a continuous strip, with the exception of one end 
left attached in situ, irritation of any part of the 
almost severed strip will cause a responsive spasm 
of the bell, so soon as the wave of stimulation has 
time to reach the latter. I next continued this form 
of section into the contractile tissues themselves, 
carrying the incision round and round the bell in 
the form of a spiral, as represented in the case of 
Aurelia by Fig. 11, page 70. In this way I con- 
verted the whole Medusa into a ribbon-shaped piece 
of tissue ;* and on now stimulating the marginal 
* It may be stated that while conducting this mode of section 
of Staurophora laciniata, the animal responds to each cut of the 
contractile tissues with a locomotor contraction (or it may not 
