658 JULIAN §. HUXLEY 
containing 50 ¢.¢. sea-water together with a certain amount 
of n/2 KCl. The results.are summarized in Table II. 
TABLE II 
+ denotes active heart-beat; (+) slow; (—) slow and intermittent ; 
— no heart-beat, The upper sign in each compartment denotes the larger 
zooid, the lower the smaller, 
No, of c.c. n/2 Minutes. 
KCl added, 15 20 30 35 40 50 70 160 
0 (control) af aI ai 3 oP at SF + 
AR a0 + a5 ie ate ete af 
2 + + ar a5 =F =F at is 
5 ap tr: a Tr i =F = 
4 Ts + + =F (+) = 
oe of =f (=>) = aaa 
8 = at a “a OG — 
+ 3 + (—) noted — 
10 + + + (-) = 
a5 =i ie (=) = 
15 + + + + (4+) = 
+ + (-) (-) () 
20 Si (—) a 
+ (=) = 
40 a9 = 
KCl thus exercises a very marked effect upon the Ascidian 
heart. The stronger action of the salt on small zooids is to 
be noted. The organisms were left in the solutions to see what 
type, if any, of dedifferentiation they showed. 
Those in the two highest concentrations died in under 
twenty-four hours without reduction ; their stolons also were 
killed or damaged. Those to which 10 and 15 e.c. KCI had 
been added were scarcely affected after twenty-four hours, 
but were dead by forty-eight hours, having previously shrunk 
very considerably and become opaque. 
In the solution with 8 ¢c.c. one had died; the other had 
started to dedifferentiate. Both stolon and zooid 
were affected (fig. 20). The zooid showed a characteristic 
sign of KCl reduction in the cellular strands extending from the 
retracted siphons to the test. Also characteristic, and directly 
dependent on the absence of circulation, was the congestion 
