PHYSIOLOGICAL CHARACTERISTICS OF AXIATE PATTERNS 109 



gram per hour; for thirds, 1.5 1, and for eighths, 2.06. It may be noted 

 here that differences in susceptibility to cyanide show similar differences 

 in long and short pieces following section. It was also determined that in 

 1/8 pieces from anterior and posterior regions of the anterior zooid, that is, 

 just posterior to the head and in the mouth region, the rate of oxygen up- 

 take is about the same a short time after section, while 23-26 hours after 

 section rate of the posterior pieces is distinctly lower than that of the ante- 

 rior pieces. Here, again, susceptibility to cyanide shows the same like- 

 ness immediately after section and lower susceptibility of posterior pieces 



TABLE 5 



Oxygen Uptake of Anterior and Posterior Halves of 

 THE Anterior Zooid and a Piece of the Same Length 

 from the Posterior Zooid Region of Dugesia doroto- 



cephala; TEMPERATURE 20° ± 1° C. 



(From Hyman, 19236) 



Number of 

 Experiment 



3 



4 

 5 

 6 



7 

 8 



9 



10 



Days since 

 Feeding 



14 

 15 

 16 



14 

 IS 

 13 



14 



Cubic Centimeters of Oxygen 

 Consumed per Gram per 24^ Hours 



Anterior 



Half of 



First Zooid 



Posterior 



Half of 



First Zooid 



Piece from 



Posterior 



Zooid 



later. These experiments show, first, that respiratory rate is increased in 

 short pieces and little or not at all in long pieces following section ; second, 

 that in pieces from the posterior region of the anterior zooid oxygen up- 

 take immediately following section is about equal to, but after 24 hours 

 lower than, that in anterior pieces of the same length. 



Table 5 gives data on oxygen uptake of pieces of equal length from 

 three regions of the planarian body, anterior and posterior halves of the 

 anterior zooid, and pieces of equal length from the posterior zooid re- 

 gion. Pieces of this length show no marked change in respiration during 

 the first 24 hours following section; consequently, the experiments were 



