262 Hans Przib 



ans rrzibrarn 



of but one jaw with but one tooth on the non-operated jaw, the 

 regenerating one showing no teeth (Fig. 6). 



A tendency toward a quick restoration of a symmetrical con- 

 dition was also found several times in experiments of Miss Zuel- 

 zer on the regeneration and moulting periods of the isopod, 

 Asellus aquaticus. When both long antennae were removed, 

 simultaneously, but at different levels (Fig. 7) they would be apt 

 to appear regenerated to an equal length (Fig. 8) even after the 

 next moult, though not having yet attained their normal length. 

 In some way these conditions may be related to the different rate 

 with which appendages regenerate from different levels. 



It is not necessary that the two correlated parts be symmet- 

 rically situated. The male of the water-newt, Triton vulgaris, 

 produces in its state of courtship a crest along its back and around 

 its tail, which has a ragged appearance (Fig. 9). Kammerer cut 

 the tail off to test the regenerative power of the secondary sexual 

 characters. He found that at first the tail appears with smooth 

 not ragged edges. But this is not all: the crest on the back had 

 also lost its ragged appearance, thus conforming with the outline 

 of the new dorsal rim of the tail (Fig. 10). It is not shed or 

 resorbed, but keeps the height of the courtship crest. 



The object of my paper is to emphasize the similarity of these 

 processes of regeneration, reduction and compensation, in lower 

 and higher animal forms, and their relation to the reestablishment 

 of the equilibrium of animal form. 



