FNLAND FISHFJMES. 63 



As a control to this experiment, several starfish, which also set 

 on June 28tli, were kept with a minimum amount of food. One 

 of these, photographed at natural size on September 6th, is shown 

 in Fig. 22 A, while the largest star in the car (with plenty of food) 

 is represented in Fig. 22 B (27 m. m.). The specimen figured in 

 A is thirty-nine days old, and that in B is within a day or two of 

 that age. 



The next experiment (illustrated by Fig. 23) on the growth of 

 stars was as follows : On August 3d two stars of average size 

 were taken from the original car and placed in another car with a 

 bunch of mussels. 



On August 3d (1) = 7 m. m. Fig. A. 



On August 16th (2) == 10^ m. m. Fig. A '. 



During this time the stars had little or no food, since they could 

 not, or Avould not, eat the mussels. On August 15tli a lot of bar- 

 nacles were placed in this car, and by September 5tli the results 

 of the new food were evident enough : 



Sept. 5 : (1) = 1^5 m. m.. Fig. C (one arm was torn oft" in meas- 

 uring). (2) = 19 m. m., Fig. C '. 



Sept. 26 : (1) — 28 m. m.. Fig. D (new arm 10 m. m. measured 

 from mouth, growth of 7 m. m.) (2) = 21) m. m.. Fig. D '. 



Oct. 12^: (1) = 36 m. m.. Fig. E (regenerating arm, 20 m. m., 

 from mouth, growth of 17 ni. m.) (2) — 11 m. m., Fig. E^ 



From August 3d to August 16th, while these specimens were 

 not growing at all, those in the car grew about 6 m. m. These 

 two specimens afterward, however, having more food and no inter- 

 ference in eating it, made up this difference, and by September 

 26th had grown as nnich as those in the original car. 



One interesting point which is brought out by the experiment 

 is that a star which is regenerating an arm may grow as fast as a 

 complete star. Compare next experiment. 



C Rate of groAvth and rate of regeneration. The starfish, like 

 the lobster and many crabs, has the habit of dropping off an arm 

 which has been mutilated, and of regenerating a new one. Unless 

 the arm is mutilated or some other shock administered, one may 



