REGENERATION 



519 



In an early embryo the nervous ayatem la not involved. However, when a formed em- 

 bryonic field ia extirpated, there is generally no regeneration. This means that at this 

 stage regeneration as a property of the embiyo ia restricted to local fields, and is not 

 related to "the organism as a whole". 



There is still a great deal of room for further study of regeneration, particularly 

 as it may be affected by mitotic inhibitors, colchicine, dlnitrophenols, specific iona, 

 pH, temperature, light (where pigment cells are involved). 



Radiated 

 ol time of 

 amputation 



Radiated 

 12 days after 

 amputation 



Fig. 1. A larva showing the stage 

 in which the right fore limb 

 was amputated. The double 

 pointed arrow Indicates the 

 level of amputation. 



Figs. 2 and 3. Larvae which were 

 given a single exposure to 

 x-rays Immediately after limb 

 amputation. Limb regeneration 

 has been completely suppressed. 



Figs. 4 and 5. Control larvae 



showing the progress of normal 

 regeneration 12 and 25 days 

 after limb amputation. Stip- 

 pling on the limb stump in 

 Figure 4 Indicates the approxi- 

 mate extent of the normal re- 

 generation blastema on the 

 twelfth day. 



Figs. 6 and 7. Larvae which were 

 given a single exposure to 

 x-rays on the twelftli day 

 after limb amputation. A 

 blastema was present at the 

 time of radiation, as shown by 

 stippling. Limb regeneration 

 was completely suppressed. 



(From Butler & Puckett I9U0: 

 Jour. Exp. Zool. 81i:223) 



days 



EEFERENCES : 



Abeloos, M., 1952 - "La re'generatlon et les problemes de la morphogenfese. " Gauthier- 



Villars, Paris. 

 Barbel', L. W. , 19*+^ - "Correlations between wound healing and regeneration in fore-limbs 



and tails of lizzards." Jour. Exp. Zool. 89:l4-Ul. 

 Brachet, J., 19^+6 - "Aspecta biochimique de la Eegene'ratlon. " Experientia II/2 . 

 Brunst, V. V. & E. A. Scheremeti Jewa, 1955 - "Unterauchung des Einflussea von Eontgen- 



strahlen auf die Eegeneration der Extremltaten beim Triton." Arch. f. Ent. mech. 



128:181. 

 Buchanan, J. W. , I9I+O - "Eegeneration." Am. Nat. Ih:k8l. 



