CHARLES F. LYTLE 327 



Figure 9 illustrates the de\'elopment and budding of two groups 

 of animals reared from 27 frustules at two different feeding rates. 

 The animals represented by the open circles were fed on alternate 

 days as in the previous experiments. They exhibited an initial phase 

 of rapid hydranth production followed by the initiation and rap- 

 id increase in frustule production— but no phase of medusa budding 

 and no decline in the rate of frustule production. Therefore, in 

 the absence of medusa budding the available food material went 

 preferentially into the production of frustules. The second peak of 

 hydranth budding during the 13th week does not appear related to 

 the absence of medusa budding in these animals, since a similar 

 secondary peak is observed at the same time in parallel groups 

 of animals grown at this temperature which do produce medusa 

 buds. 



26t2°C 



i=8= 



H y d r a n t hs 



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20 



15 



10 



5 







0.5 



Frustules o 



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Medusae 



8 ID 12 14 



WE EKS 



Fig. 9. Budding pattern of colonies reared from 27 frustules at two 

 different feeding rates. Colonies represented by the open circles were fed 

 on alternate days and those represented by the filled circles were fed every 

 third day. 



