Metamorphosis of Axolotls 
59 
The intestine. 
The alimentary duct of Anura undergoes considerable changes 
during transformation; the long and spiral intestine of the tadpoles 
becomes suddenly shorter and it is transformed into the intestine 
of the full-grown form. This interesting process has been the object 
of few investigations x ). According to Reuter, the sudden decrease 
of length and volume of the larval intestine, occurring during 
metamorphosis, sets in at the stage between the appearance of the 
first and the second pair of limbs. This decrease takes place first 
in the spiral of the intestines and the duodenum. The processes of 
decrease occur rapidly, they last 24 to 48 hours. Animals take no 
food during the period of decrease; in connection therewith, we 
observe atrophy of fat stores. The beginning of degeneration of 
the intestine consists in diminished ability of resorption and secretion 
which is characterised by the appearance of numerous „round 
cells“ and the atrophy of the cells as well as the development of 
gigantic cells. The spiral of the intestine becomes shorter and 
narrower, owing to contraction of muscles; by this means the 
gigantic cells come near each other and the dead epithelial ceils 
are thrust into the interior. 
In a description of changes in the intestine of tadpoles during 
metamorphosis, Reichenow states that the rapid degeneration of 
the epithelium, occurring during that period, should be referred to dis¬ 
turbances in the alimentation of that tissue, caused by contraction of its 
muscles. But the author does not explain the cause of these contrac¬ 
tions, so that the phenomenon of degeneration of the intestine during 
metamorphosis remains obscure. We may perhaps understand these 
processes, if we take into consideration the results of experiments made 
on animals subjected to starvation. Morgulis observed that com¬ 
plete starvation causes considerable shortening of the intestine in the 
amphibian Diemyctylus viridescens. In a paper on the acceleration 
of moulting by starvation, V. Ruzicka gives photographs from 
which we gather that the tissues of the intestines of newts subjected 
to starvation undergo considerable reduction; the epithelial part of 
*) As to Urodela , no data are known referring to the behaviour of their 
intestine during metamorphosis. But since authors agree that Urodela become 
thinner during transformation, I suppose that in their alimentary duct too, as 
well as in that of Anura, changes occur. 
