CHARLES F. LYTLE 321 



211 2 C 



15 



10 



5 







.7 5 



.50 



.25 







Hydranths 



O o o- 



Frustules 



- o o- 



-O O O o o o 



-o o^,^^ 



°-, Medusae 



6 8 10 12 14 16 



WEEKS 



Fig. 4. Budding pattern of 15 polyps reared at 27°(d=2 ). Values on the 

 abscissa represent the number of buds of each type produced per colony. 



start of this experiment and cultured at 27° (± 2°). All frustules 

 had differentiated into polyps and produced an average of two 

 hydranths each by the end of the first week. Hydranth budding 

 declined during subsequent weeks but increased to a second peak 

 during the 13th week. Frustule production began during the sixth 

 week and declined to a minimum during the tenth week before ris- 

 ing to a new high during the 15th week. Medusa buds appeared 

 during the seventh week ( immediately following the decline of frus- 

 tule production) and were produced continuously through the 16th 

 week. 



The basic sequence of events exhibited by these colonies was an 

 initial phase of rapid hydranth production, a phase of rapid frus- 

 tule production, and a phase of medusa budding. Secondary in- 

 creases in hydranth budding and frustule budding were also ob- 

 served during the latter portion of the phase of medusa budding. 



