ALLISON L. BURNETT 431 



The budding pattern may operate through the following mech- 

 anism. When a bud first begins its development an inhibitive prin- 

 ciple is released. This principle does not permit the formation of 

 another bud in adjacent regions of the parent column. As the bud 

 continues to grow it forms tentacles and eventually a peduncle; at 

 this time a second bud begins to form on the opposite side of thr 

 parent stalk. Presumably, the peduncle inhibits the flow of the in- 

 hibitive principle back to the parent stalk, also the principle 

 which has previously diffused back into the parent before peduncle 

 formation, is more concentrated on the side of the stalk adjacent 

 to the bud than on the opposite side. The third bud will form on the 

 opposite side of the stalk and above the second bud. Again, the 

 formation of the third bud does not occur until much of the energ>^ 

 supply of the second bud in the form of food reserves is depleted, 

 and the second bud has begun tentacle and peduncle formation. 

 Such a mechanism makes it virtually impossible for two buds to 

 compete for food materials from the same area of the parent col- 

 umn. However, the author has observed that under conditions of 

 extremely rich feeding, it is not unusual for two buds to begin to 

 form simultaneously from the same level of the parent stalk and di- 

 rectly opposite one another. Since both buds have begun to form 

 simultaneously, their inhibitive principles will have no effect upon 

 one another. 



Furthermore, the presence of an inhibitive principle explains 

 why cells which pass from the budding region down into the 

 jDeduncle have a low metabolic activity, are highly vacuolated, 

 and contain few food reserves. First, most of the food reserves which 

 were originally in these cells have been utilized during bud for- 

 mation. Secondly, subsequent ingestion of food by the hydra will 

 not nourish the peduncular cells because they are under the di- 

 rect growth inhibiting action of the neighboring budding region and 

 do not require large amounts of food for the upkeep of this metabol- 

 ically inactive region. If the peduncle is excised from the body 

 column it will never completely regenerate into a normal hydra 

 because of a lack of energy reserves. An excised peduncle is capa- 

 ble of forming only 2 or 3 tentacles when excised from the inhibiting 

 action of the budding region. 



