Metamorphosis of Axolotls 
65 
cimens. Morgulis says that, during winter-sleep, the animals con» 
sume their adipose tissue; on the other hand, during experimental 
starvation, they destroy albuminous substances from the muscles 
and sugar from the liver. 
The rapid emaciation of animals fed on thyroidine and, in the 
experiments of Laufberger, Romeis and Cottronei, even 
their death, bear witness to a toxic influence of that substance. 
Small doses of thyroidine cause relatively small disturbances in 
the organism which lead to metamorphosis; larger ones, especially 
when given to young specimens, produce exhaustion which ends in 
death. I therefore supposed that other chemical agents which in¬ 
fluence metabolism might also cause metamorphosis in axolotls 1 ). 
Salicylic acid is known to accelerate metabolism and to cause 
autolysis of tissues, so I hoped to succeed in producing transform¬ 
ation by feeding axolotls on this substance. To one black axolotl 
meat was given together with small doses of salicylic acid (about 
0'2 gr.) during five months at irregular intervals. The effect was 
remarkable: after a few days considerable shortening of the gills 
was observed. This decrease proceeded slowly as long as the anim¬ 
al was fed on salicylic acid and came to an end when that sub¬ 
stance ceased to be given. It was impossible to give salicylic acid 
at short intervals or in larger doses since it was injurious to the 
organism (the animal looked very feeble). From time to time, I had 
to interrupt salicylic acid treatment; and that was why the trans¬ 
formation lasted so long. On March 21 st , 1918, the animal was put 
into a terrarium, when only small fragments of its gills and fin 
were visible. 
The process of metamorphosis of the specimen fed on meat with 
salicylic acid had a different course from that in axolotls fed on 
meat with thyroidine. Even the slightest doses of thyroidine may 
start transformation; and these morphogenetic phenomena may be 
compared with phenomena of the „isobolic system“ of physiologists. 
The decrease of larval respiratory organs in individuals fed on sal¬ 
icylic acid was proportional to the doses of the substance given 
and did not continue unless salicylic acid was given. The differ- 
!) This supposition is supported by Wintrebert’s observation that tadpoles 
kept in water containing radium or its emanation undergo metamorphosis earlier 
than usual. 
Bulletin III. B. Janvier—Mars. 
5 
