DYNAMICS OF MORPHOGENESIS 415 



all cases the determination for each size and each time has been 

 made repeatedly so that conclusions do not rest on single series 

 and besides this the results of these experiments are amply con- 

 firmed by large numbers of others in which only certain regions 

 of the body instead of the whole were used in susceptibility 

 determinations in relation to size and region. 



In the susceptibility determinations, as stated the whole body ex- 

 cept the head was cut into fourths, sixths, etc., and the susceptibility 

 of all pieces was determined and recorded, but in the following 

 tables only the pieces from the first zooid (see Child 'lie) are 

 included. The pieces of the posterior zooids show nothing funda- 

 mentally different from those of the first zooids and double the 

 length of the tables. Only a sufficient number of susceptibility 

 records are given to show the general course of the changes in 

 susceptibility. The tables of these records given below are sup- 

 plemented and confirmed by many other similar series in my notes. 



The tables are in the form of the susceptibility tables in an 

 earlier paper (Child '13 a). The column headed ''length of time" 

 gives in hours and minutes the length of time that the animals 

 or pieces have been in the solution at each observation. The 

 column headed "lots" gives the serial numbers for each time of 

 the different lots of ten each, beginning with the most anterior 

 pieces as Lot 1. The lot-numbers are the same as the numbers 

 of the pieces in the corresponding figures. 



The five columns headed "I to V" under "stages of disinte- 

 gration" distinguish more or less arbitrarily five stages in the 

 visible changes which the animals undergo in dying. These 

 five stages are briefly as follows: 



I. Still intact, showing no appreciable disintegration. Such 

 animals or pieces are always alive and moving about. 



II. In whole animals, from the first traces of disintegration to 

 the beginning of disintegration along the margins of the body, 

 which usually follows disintegration of the head. In pieces from 

 the beginning of disintegration at one or both ends to beginning 

 of disintegration along the lateral margins. Considerable motor 

 activity may still be present. 



