On the Nervous System of Cassiopea Xamachana. 



161 



The pulsation-rate of active specimens frequently reached its 

 maximum at from 27 to 29 C. In other specimens the maximum rate 

 was not attained until a temperature of 37 C. had been reached, 

 after which the decline in rate was precipitous, death occurring at 38.5. 



A summary of all the results is given in figure 15, which shows the 

 average for 11 active and 9 activated half-disks. 



RELATION BETWEEN AREA OF TISSUE ENERVATED BY A 

 SINGLE SENSE-ORGAN AND RATE OF PULSATION. 



Eimer (1874) made the observation that as the area of tissue ener- 

 vated by a single sense-organ was progressively decreased there was a 

 corresponding decline in the rate of pulsation. He states that the de- 

 cline in rate is directly proportional to the decrease in area through 

 the range of the experiment. 



Romanes (1895) repeated these observations and denied the con- 

 clusion of Eimer that the decline in rate was directly proportional to 

 the decline in area; but he did not give any definite statement of the 

 mathematical relation between area and rate of pulsation. Mayer 

 (1906) confirmed and extended these latter observations, but again 

 did not accurately determine the relation 

 between tissue area and rate of pulsation. 



In my own experiments all sense-organs 

 but one were removed from each disk, and 

 after allowing a period of 1 hour for recovery 

 from the shock of the operation the rate of 

 pulsation was recorded. Immediately after 

 this record was completed the area under 

 the control of the sense-organ was reduced 

 to one-half its former extent by making a 

 cut through the subumbrella tissues. In 

 this manner the area of tissue was reduced 

 to -L 4-, 4, and T V of that of the entire Fl - is. showing method of opera- 



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disk (fig. 16) and a record of the pulsation- 

 rate was secured for each area. In all, 141 

 disks were used in this series of experiments. 



A summary of the results is given in table 14 and figure 17. 



As will be seen from the graph, the decline in rate follows a right line 

 very closely, except at the point where the rate for | the original area 

 is shown. When extended to included areas of tissue less than T V 

 of the original the decline in the pulsation-rate follows practically the 

 same formula as shown in figure 17, by the broken line extending to a 

 point where the tissue area under the control of the single sense-organ 

 is reduced to -^ the original size. 



A reduction of the area of a disk beyond T V of the original could 

 not be made accurately by the operation illustrated in figure 17. 



tion employed in studying the 

 relation between area of tissue 

 innervated by a single sense- 

 organ and the rate of pulsation. 



