40 
L. Kaufman: 
(from Richter’s factory); each tabloid, containing 0*5 gr. of 
thyroidine, was divided in two parts; one fragment of thyroidine 
(about 0*25 gr.) was >given to the animal every two or three days r 
this being the most suitable dose. Gu der hats ch, Laufberger 
and Cotronei fed their animals on fresh or dried glands, only 
Romèis, as far as I know, used dry preparations in the form of 
tabloids, but he did not determine the weight given to a tadpole. 
Romeis’ method of proceeding is convenient owing to facility of 
dosing. 
3. Obseiwations on Hying animals. 
Twelve axolotls were made to undergo metamorphosis by feeding 
on thyroidine; with respect to them I give the following data from 
my notes. 
No. B. Black axolotl ; length 13*5 cm. ; meat with thyroidine (0*25 gr.) given 
on May 28 and 31, on June 1, 4, 6, 7, 8 (about 0T25 gr.),. 9 and 13, 1916. 
On June 12, I observed the inchoative reduction of the gills and fins. Without 
being transferred into a terrarium, it underwent metamorphosis. 
First moult on June 17. 
No. 4. White axolotl; length 20*5cm. ; it already laid eggs. Thyroidine given 
on June 22, 24, 26: 0*25 gr., on 29: 0*125 gr., on July 1 and 6: 0*5 gr. The two 
last doses were too large; the animal’s skin became hyperaemic; the animal came 
often to the surface of the water and gulped air. Its movements were abnormal; 
several days it swam with its head downwards. It lost its fin almost completely, 
the size of its gills was reduced; on July 13 it died. With the exception of this 
specimen, only one animal died when fed on thyroidine; it was a female which 
had laid eggs in the spring of 1917 ; in August, fed on normal doses of thyroidine, 
it underwent an almost complete transformation, but died before having achieved it. 
I observed that the animals experimented upon became thinner 
and I began to weigh them, in order to ascertain w'hether a con¬ 
nection exists between thyroidine feeding and loss of weight. 
No. 5. White axolotl; length about 15 5 cm., weight 35*7 gr. Meat with thyro¬ 
idine (0*25 gr.) given on September 2, 4, 5, 7, 9, 12, 16, 17,. 20 and 25. Almost 
entirely transformed (fragments of gills and fins remaining); when normally fed 
and not transferred to a terrarium, did not regenerate its larval respiratory organs. 
On Oct. 9 brought in shallow water: on Oct, 12 complete metamorphosis. 
Weight = 22 gr. The animal therefore lost 37°/ 0 . of its initial weight. 
No. 6. White axolotl; length 16*5 cm., weight 43'7 gr. Meat with thyroidine 
given on Sept. 2, 4, 5, 7, 9, 12 and 17 (0 25 gr.) and on 20: 0*125 gr. On Sep¬ 
tember 28 put into a terrarium, transformed. On October 5 it weighed 26*3 gr., 
having lost nearly 40°/ 0 of its former weight. 
No. 8. Black axolotl; length about 19cm., weight 54*3gr. Fed on thyroidine:. 
on September 4: 0*125 gr., on September 25: 0*25 gr. and on October 9: 0*125 gr. 
