12 



LEWIS R. CARY 



EXPERIMENTS OF TYPE lA AND 2A 



Mayer ('06) has pointed out the fact that in a disk of Cassiopea 

 a single marginal sense organ will control pulsation just as 

 effectively as will the sixteen normally present. His "studies have 

 shown besides that the most rapidly discharging sense organ 

 really determines the rate of pulsation in a normal medusa. 

 The experiments of type la and 2a were undertaken to deter- 

 mine whether or not a single marginal sense organ would show 

 the same influence on the rate of regeneration as upon pulsation. 



s.o. 



s.o 



Figs. 5 and 6 To show the operation used in experiments of types la and 2a. 

 In figure 5 one sense organ only is left but its influence can be transmitted through- 

 out the disk. In figure 6 a single sense organ is left while the two halves of the 

 disk are insulated so that the influence of the sense organ is confined to one-half. 



The results obtained from the experiments of type la (fig. 4) 

 were, as in all the experiments with entire disks, inconstant. 

 Usually disks with their sense organs intact regenerated most 

 rapidly. In a relatively small number of pairs the rate was the 

 same for each member of a pair and in two instances the disk 

 without sense organs regenerated faster than the one upon which 

 the sense organs remained. Here again as in experiments of 

 type 1 the individual variation in physiological activity of the 

 different disks affords an explanation of the irregularity of the 

 results obtained. 



