Sfndifs on Regulation ^QI 



sents the condition of a normal animal after about four and one- 

 half months without food; Pig. 13 shows a piece including 

 almost the whole body except the head after the same length of 

 time without food. Shorter headless pieces differ still more widely 

 from the normal animal; Fig. 15 shows a short, headless, pre- 

 pharyngeal piece after twenty-six days of starvation and Fig. 18 

 a headless postpharyngeal piece without pharynx after sixty-five 

 days. In these pieces total, or almost total, disappearance of the 

 intestinal branches has occurred in a period of time from less than 

 one-sixth to about one-half that necessary for intestinal reduction 

 in the normal animal to the condition shown in Fie. 6. 



O 



Such differences as these cannot be due to differences in nutri- 

 tive conditions. The normal animal is more active and must use 

 a greater amount of nutritive material in proportion to its size in 

 a given time than a headless piece such as that shown in Fig. 13, 

 and its activity and nutritive requirements must be many times 

 greater than those of the headless pieces shown in Figs. 15 to 17 

 and 18 to 20, in which movement is slight, yet in all of these pieces 

 intestinal degeneration is more rapid than in the normal animal. 



Moreover, in' headless pieces the rapidity of intestinal reduction 

 increases with decrease in the length of the piece. The long piece 

 in Fig. 13 (all that part of the body posterior to a in Fig. i) reaches 

 the condition shown in 143 days, the piece shown in Figs. 18 to 20 

 (that part of the body posterior to g in Fig. i) loses all traces of 

 intestinal branches in sixty-five days, and the piece shown in Figs. 

 15 to 17 (that part of the body between d and e in Fig. i) loses all 

 traces of intestinal branches in less than forty days (Fig. 15, 

 twenty-six days). In these pieces, and in all similar pieces 

 observed, the rapidity of degeneration of intestinal branches is 

 in general inversely proportional to the length of the piece. 



At the time of section the amount of nutritive material in these 

 various pieces must be about the same in proportion to their size. 

 Of course some differences exist in this respect and there is more 

 loss from the wound in some cases than in others, but contraction 

 is usually so rapid that loss from the wound is slight. The two 

 pieces whose history is given in Figs. 15 to 17 and Figs. 18 to 20 

 were taken from the same worm; nutritive conditions must there- 



