436 CM. CHILD 



This also is to be expected, for the piece is no longer in con- 

 nection with its chief sources of stimulation, that is, first the head 

 region and secondly other parts of the body. As regards move- 

 ment it is much less active than the intact animal and if it were 

 not for the wounds at its ends and the growth processes beginning 

 there its rate of metabolism would undoubtedly fall far below 

 that of the uninjured animal. 



2. The temporary increase in rate of metabolism following section 

 varies in amount inversely as the length of the piece. 



A comparison of tables 2, 5, 9 and 13 will show that in general 

 the smaller the pieces the higher the susceptibility. The one- 

 fourth pieces show in the tables practically no increase in sus- 

 ceptibility following section. As a matter of fact the regions 

 adjoining the cut ends do show an increased susceptibility but it 

 does not involve the piece as a whole. 



That the shorter piece should be more stimulated tha i the 

 longer by section is also in accord with expectation. The shorter 

 the piece the more direct the injury and resulting stimulation of 

 its conducting paths and tissues. In very short pieces almost 

 the whole length becomes involved in the wound reaction at the 

 two ends. Tables 10 and 14 show that the susceptibility of the 

 one-eighth and one-twelfth pieces does not fall during the forty- 

 eight hours following section to so low a level as that of the longer 

 pieces. This difference is undoubtedly due to the fact that in 

 the shorter pieces the wound reaction affects the whole rather 

 than merely the two terminal regions as in the longer pieces. In 

 the long pieces the susceptibility of the two terminal regions is 

 distinctly higher than that of the rest of the piece at this stage. 



3. The temporary increase in rate of metabolism following section 

 varies in amount according to the region of the original body which 

 the piece represents, being least in the most anterior and increasing 

 in successively more posterior pieces. 



This regional difference in stimulation is associated with length 

 of piece and is not apparent in the long one-fourth pieces, but in 

 the one-sixth, one-eighth and one-twelfth pieces it is distinct. 

 The rate of metabolism in the first zooid of uninjured animals is 

 highest in the anterior region and decreases more or less regularly 



