424 L- H. IIYMAN. 



evidence indicates that the mass of regenerated tissue is not 

 proportional to the original mass of the piece but to the contrary 

 is relatively greater the smaller the latter. In view of all of the 

 facts it is practically certain that the apico-basal sequence in 

 rate of elongation observed in Obelia pieces is the result of differ- 

 ences in level. Even though the time occupied by the elongation 

 process may be the same at different levels, as insisted by Lund, 

 still the length of outgrowth produced in that time is greater the 

 the more apical the piece; and hence the "rate of regeneration," 

 even using this expression as defined by Lund, decreases apico- 

 basally in Obelia as in other lower forms. 



SUMMARY. 



1. The rate of oxygen consumption per unit volume of cceno- 

 sarc is greater in apical than in basal halves of distal regions of 

 the stem of Tubularia. 



2. The rate of oxygen consumption per unit volume of coeno- 

 sarc is greater the younger the stem (smaller its diameter). 



3. The time between cutting and completion of oral hydranths 

 is shorter the more apical the piece in pieces of equal length from 

 distal levels of the stem of Tubularia. 



4. The statement in 3 may or may not hold for proximal 

 regions of the stem, depending on the species. 



5. The time between cutting and completion of oral hydranths 

 is independent of the length of the piece when the apical end of 

 the pieces is taken at the same level, except in very short pieces. 



6. The time between cutting and completion of oral hy- 

 dranths is shorter the younger the stem (smaller the diameter). 



7. The size of the regenerated oral hydranths is almost entirely 

 independent of the length of the piece, when the apical end of 

 the pieces is taken at the same level, except in very short pieces. 



8. The size of the regenerated oral hydranth is slightly smaller 

 especially as to width the smaller the diameter of the stem but 

 not proportionally smaller. 



9. The size of the regenerated oral hydranth is absolutely 

 larger on apical than on basal pieces of equal mass taken from 

 distal regions of the stem. 



10. In general there is a relation between respiratory rate and 



