448 Max Mapes Ellis 
4 The rate of regeneration increased directly with the level 
of the injury, as the level of injury moved cephalad from the tip of 
the tail. ‘The removal of 20 mm. of tail constituted a fatal injury 
to tadpoles whose tail length was 26 mm. 
5 Other factors being the same, the amount regenerated varied 
in the same direction as the temperature, between 66° and 84° F. 
6 There is a temperature limit below which tadpoles will 
live but do not regenerate the tail. This limit was between 57° 
and 66° F. 
7 There are four distinct periods of regeneration: (1) the 
first of slow regeneration during the first few days after the opera- 
tion; (2) the second of rapid regeneration; (3) a third in which the 
regeneration is much slower than the second; (4) a last period in 
which the processes of regeneration gradually cease. 
8 ‘The time elapsing between the operation and the cessation of 
regeneration, that is, the period of regeneration, varies with the 
level of injury. The higher the injury the longer this period; 
though the period is relatively longer for the series operated upon 
at the lower levels. 
BIBLIOGRAPHY 
BroussoneT, 1786—Observations sur la régénération de quelques parties du 
corps des Poissons. Hist. de l’Acad. Roy. des Sciences. 
Dursin, Marton ’og—An Analysis of the Rate of Regeneration throughout the 
Regeneration Process. Jour. Exp. Zodl, vol. vii- 
Exits, Max M. ’08—Some Notes on the Factors Controlling the Rate of Regenera- 
tion in Tadpoles of Rana clamitans. Biological Bulletin, vol. xiv. 
KamMERER, Paut ’05—Ueber die Abhangigkeit des Regenerationsvermégens der 
Amphibienlarven von Alter, Entwicklungsstadium und _spezifischer 
Grosse. Roux’s Archiv f. Entw. Mech., Bd. 109. 
Kinc, Heten D. ’98—Regeneration in Asterias vulgaris. Roux’s Archiv f. Entw. 
Mech., Bd. 7. 
Morcan, T. H. ’o2—Further Experiments on the Regeneration of the Tail of 
Fishes. Roux’s Archiv f. Entw. Mech., Bd. xiv. 
’06—Physiology of Regeneration. Jour. Exp. Zodl., vol. iii. 
SPALLANZANI (Lazaro) Assé 1769—Prodromo. An Essay on Animal Repro- 
ductions. Translated from the Italian by M. Maty, London. 
StockarD, Cuartes R. ’o8—An Experimental Study of the Rate of Regeneration 
in Cassiopea xamachana. Carnegie Institution Publications. 
