EXTERNAL FACTORS OF REGENERATION IN ANIMALS 31 



the water, regeneration takes place at the cut-ends. If a piece is 

 suspended with its apical end upwards (Fig. 14, B\ a new stem devel- 

 ops at the upper cut-end, and new roots from the lower cut-end. 

 If a piece is suspended with its basal end upwards (Fig. 14, C), there 

 is formed at its upper (basal) end a new stem with its branches also 

 slanting upwards as shown in the figure. Roots appear at the 



\ 



FIG. 14. After Loeh. Normal stalk of Antennularia antennina. B. Piece regenerating in vertical, 

 normal position. C. Piece regenerating in inverted position. D. Piece regenerating in in- 

 clined, vertical position. E. Piece regenerating in inclined, inverted position. A Piece 

 regenerating in horizontal position. 



lower (apical) end. Since gravity is the only force that acts in a 

 vertical direction under the conditions of the experiment, Loeb con- 

 cluded that it plays an important r61e in determining the kind of 

 regeneration that takes place. Its action is of such a nature that a 

 new stem develops from the upper cut-end, and roots from the lower 

 end, regardless of whether the upper end is the basal or the apical 

 end of the piece. Similar results are also obtained, according to 



