108 



C. M. CHILD 



TABLE 2 



Series 494- Worms 18 mm., in laboratory six months before experiment. I. Con- 

 trol in water; II. Whole loorms in KCN 'ml200000 five minutes bejore section, 

 pieces cut in this solution and kept jorty-eight hours in same concentration 



pieces of the controls as compared with I c in Tables 3, 4, and 5, 

 where the c pieces are in almost all cases wdthin the first zooid, 

 shows the influence of the posterior zooid region in increasing 

 head-frequency. 



The next three series, 489, table 3, 457 table 4 and 432 

 table 5^ include only three pieces, a, b, c, which represent ap- 

 proximately the body of the first zooid. The c pieces in these 

 series are usually wholly or almost wholly within the first zooid, 

 aIth(Aigh the difference in level of the fission plane in different 

 worms of the same size as indicated by the bracket m in figure 

 9, is such that occasionally these pieces include a portion of the 

 the second zooid. The pieces in these series are then slightly 

 shorter than the I pieces of the two preceding series. In the 

 controls I a-c of these three series it will be observed that there 

 is a progressive shift downward in head-frequency from a~c, 

 a characteristic feature to which attention has been called in 

 earlier papers (Cliild '11a, 'lib). The c-pieces show a lower 

 level of head-freciuency than in Series 512 and 494 above be- 

 cause they are usually within the first zooid. 



Series 489, table 3, shows the difference in effect of a given 

 low concentration of KCN when the pieces are cut in it (II) 



