Metamorphosis of Axolotls 
67 
lösendes Moment der degenerativen und metaplasti¬ 
schen Prozesse aufzufassen, sondern vielmehr umge¬ 
kehrt: die letzteren (verursacht durch uns zunächst 
noch unbekannte Veränderungen der strukturellen 
und chemischen Organisation der Zellen sowie durch 
Umgestaltung des Stoffwechsels) bilden den Ausgangs¬ 
punkt für den unserer direkten Beobachtung zugäng¬ 
lichen Erscheinungskomplex der Metamorphose“. 
If our hypothesis is true, starvation of the larvae should accel¬ 
erate metamorphosis, since it cooperates with that factor. In the 
papers bearing on the subject, data concerning the influence of starv¬ 
ation on metamorphosis do not agree with one another. Barfurth 
has ascertained experimentally that starvation accelerates the last 
stages of transformation. Bataillon, on the contrary, brought up 
tadpoles of Alytes wdth a first pair of limbs during 18 months with¬ 
out food. He concludes that hunger rather retards metamorphosis. 
The same view is maintained by Tornier who adduces ob¬ 
servations on tadpoles having one pair of limbs, fed on algae. Con¬ 
sidering these contradictory results, we have to remember the age 
of the tadpoles used in respective experiments. Barfurth studied 
last stages of transformation; his results demonstrate that starvation 
can accelerate the course of histolytical processes already initiated 
in the organism; it intensifies the factor which starts them. The 
tadpoles in the experiments made by Bataillon and Tornier 
were at a lower stage of development; the resorption of their tis¬ 
sues had not begun. Hunger hinders probably the normal evolution 
of animals and impedes simultaneously the appearance of the factor 
which causes rapid disassimilatory processes leading to resorption 
of the gills. In indirect connection therewith are the observations 
of Bâbâk who found that a removal of the hypophysis hinders 
metamorphosis only when the specimens pnder experiment had not 
yet their second pair of limbs. From Maurer’s paper we know 
that, during this very period, the thyroid gland is definitely formed. 
Since Adler proved that the removal of the hypophysis causes 
atrophy of the thyroid gland, the supposition seems natural that 
hunger, when acting on animals with one pair of limbs, whose tbyr- 
oidea is not yet formed, retards the development of that gland 
and at the same time delays metamorphosis; when acting on tad- 
5 * 
