REGENERATED ANTERIOR LIMBS IN THE FROG. 169 



Early observers 1 have shown that in the Urodeles, the second 

 digit is the first to appear in the process of regeneration, then the 

 first, and subsequently the third and fourth digits. More re- 

 cently, Ridewood has recorded a similar sequence in the develop- 

 ment of the regenerated digits of the posterior limb of the midwife 

 toad. 



The concealed position of the anterior limb in the gill-chamber 

 in the frog, makes the observation of sequence in the develop- 

 ment of the digits difficult ; but in the anterior limb, that region 

 which appears first in the posterior limb of the toad and of the 

 Urodele, is the one that in the frog is often wholly lacking. 



Ridewood 2 has figured a case of regeneration in the skeleton 

 of the posterior limb of the toad that shows that the limb is in- 

 herently capable of complete regeneration, and doubtless regenera- 

 tion of the anterior limb may be much more complete in the frog 

 than would appear from Figs. 2 and 3. Inasmuch, however, as 

 these figures illustrate regeneration after amputation of the ante- 

 rior limb when it was but very imperfectly formed, they indicate 

 a marked tendency toward early loss of regenerative power. 



BROOKLYN, NEW YORK, 

 March, 1904. 



1 Gotte, A., " Ueber Entwickelung und Regeneration des Gliedmassenskelets der 

 Molche." Leipzig, 1879. 



Strasser, " Zur Entwickelung der Extremitiitenknorpel bei Salamandern und Tri- 

 tonen. Morph. Jahrb. , Ed. V., Leipzig, 1879. 



2 Ridewood, \V. G. , "On the Skeleton of Regenerated Limbs of the Midwife 

 Toad (Alytes obstetricans)." Proceedings of the Zoological Society of London, Feb. 

 15, 1898. 



