STUDIES ON THE DYNAMICS OF MORPHOGENESIS 291 



In general the course and rapidity of the regulatory processes 

 and the character of the result in any region of the body differ 

 according to the size of the piece. 



From these considerations it becomes evident that we cannot 

 separate entirely the factors of size of piece and region of 

 body in the different pieces. What occurs in a given piece from 

 a certain region is dependent upon its size, and what occurs in a 

 piece of given size — at least below a certain maximum — is depend- 

 ent upon the region of the body from which it is taken. More- 

 over, as will appear later, both these factors can be modified 

 experimentally by a variety of conditions. 



4- Tabulation and graphic presentation of data 



By separating a number of individuals of similar size and 

 physiological condition into corresponding pieces and determin- 

 ing the number or the percentage of cases which fall under each 

 of the groups distinguished in section 2 above, it is possible to 

 obtain general expressions for the frequency of each form of 

 regulation under given conditions and from these curves can be 

 plotted if desired. In the present section certain of my results 

 are presented in this form in order to bring out more sharply the 

 factors which limit the regulatory capacity. 



In table I the results of the most extensive group of experiments 

 performed at one time are given. This group of experiments 

 consisted of fifty worms all 16-18 mm. in length, all with post- 

 pharyngeal region longer than the prepharyngeal and all col- 

 lected on the same day, June 16, 1909, from the same locality and 

 cut into pieces two days later. Of these fifty worms ten were 

 cut into four pieces of equal length (ser. 201; fig. 17, ae, ei, im, 

 mq), ten were cut into six pieces (ser. 200), ten into eight pieces 

 (ser. 198; fig. 17, ac, ce, etc.), ten into twelve (ser. 199) and ten 

 into sixteen pieces (ser. 197; fig. 17, ab, be, cd, etc.), a total of 460 

 pieces. The old head region was of course excluded in all cases. 

 For the purpose of direct comparison with the results of other 

 series the results are given in the table of percentages, but since 

 each set consisted of ten pieces, the percentages divided by ten 



