398 L. H. HYMAN. 



emerging from the cysts. Three lots of each size were used. 

 The worms were all taken from the same stock. The results are 

 given in Table II. The heads were not removed in these cases, 

 since the worms were also used for another experiment. 



The table shows that the small worms consume 100 per cent, 

 more oxygen than the large worms. The greater difference in 

 this case than with the preceding species is probably due to the 

 greater reorganization involved in the production of young 

 worms with this species. As shown in another paper (Hyman, 

 'IQC), the process of regeneration of itself brings about a great 

 increase in the rate of oxygen consumption. 



IV. EXPERIMENTS WITH Planaria maculata. 



The so-called species Planaria maculata lives in the eastern 

 United States under stones in ponds and in the Chicago region 

 on submersed vegetation. It is highly probable that these two 

 are not the same species as Planaria maculata from the Chicago 

 region has never been found sexually mature, while that from 

 Massachusetts is sexually mature and lays capsules all summer 

 long; further the behavior of the two in regeneration is quite 

 distinct. The forms used in this experiment were collected 

 from a pond at Falmouth, Mass., and the experiments were per- 

 formed at the Marine Biological Laboratory, Woods Hole, Mass., 

 I am indebted to the director, Professor F. R. Lillie, for a research 

 room in this laboratory. 



Sexually mature worms, young worms, and egg capsules were 

 collected at Falmouth and brought to Woods Hole. The rate 

 .of oxygen consumption of the mature worms was tested with one 

 exception soon after they were collected. The young worms 

 collected, together with those which subsequently emerged from 

 the capsules, were kept for some time and fed at short intervals 

 on liver (mostly fish liver) until a considerable number of them 

 were at hand, whereupon their rate of oxygen consumption was 

 determined. In all cases the heads were removed at least several 

 hours before the test. 



The results are recorded in Table III. The young worms 

 consume about 50 per cent, more oxygen than the sexually 

 mature individuals. 



