172 STUDIES IN GENERAL PHYSIOLOGY 



minimal size, is cut from Tubularia mesembryanthemum, 

 and both its ends are surrounded by water, a head is formed 

 at both ends (Fig. 16). The head is usually formed more 

 rapidly at the oral than at the aboral end. In this way it is 

 possible to produce any number of bioral animals without 

 interfering with their vitality. 



b) If a piece of root is carefully separated from the base 

 to which it was attached, so that it is surrounded on all 

 sides by water, a head is formed at its aboral end. The root 

 continues to grow but forms no polyps if it is allowed to 

 attach itself anew as a root. 



2. If a portion of the stem is cut from Aglaophenia and 

 suspended vertically in the aquarium, it always forms a root 

 at its lower end, according to observations made thus far; it 

 matters not whether the apical or the basal end is directed 

 downward. Either a tip or a root is formed at the end directed 

 upward (toward the zenith), but a tip is formed the more 

 readily when the apical end is directed upward. 



It is therefore possible to create biapical and bibasal 

 forms (Figs. 17 and 18) in Aglaophenia; yet the certainty 

 with which bibasal animals can be created is greater than 

 that with which biapical animals can be produced. 



3. If the stems of Plumularia pinnata are cut off close to 

 the root and fixed in a vertical position, but with the tip 

 downward, a new tip instead of a new root may arise from 

 the basal end, which continues to grow upward ; more fre- 

 quently a root first springs from this end, from which arises 

 a stem that grows upward (Fig. 20, a, b). 



4 a) If a piece is cut from the stem of Eudendrium, and 

 both ends are surrounded by water, new tips are formed at 

 both extremities (Fig. 21, a, b). Yet a variation occurs at 

 times which I have not observed in the beforementioned ani- 

 mals; namely, a new tip and a new root may grow from the 

 same cut end. 



