THE INFLUENCE OF FEEDING THE ANTERIOR LOBE OF 



THE HYPOPHYSIS ON THE SIZE OF AMBYSTOMA 



TIGRINUM. 



By EDUARD UHLENHUTH. 



{From the Laboratories of The Rockefeller Institute for Medical Research.) 

 (Received for publication, November 19, 1921.) 



In a previous article^ I have shown that feeding the anterior lobe 

 of the hypophysis of cattle to metamorphosed salamanders not only 

 produces a far higher rate of growth than does the feeding of earth- 

 worms, but causes the animals to grow beyond the known maximum 

 size of the species. The purpose of the present paper is to report on 

 the results of a continuation of the experiments on Amby stoma 

 ligrinum. 



Ilypophy sis-Fed Animals Compared with Normal (Worm-Fed) 



Animals. 



Figs. 1 and 2 show the animals of Experiment 1 at an age of 88 

 weeks. In Fig. 1 are shown the three worm-fed controls, in Fig. 2 the 

 two hypophysis-fed animals. Total length, weight, and sex are 

 indicated in the figure legends. In comparing the controls with the 

 experimental animals it will be noticed that hypophysis-feeding 

 resulted in a larger size than the feeding of normal food. Figs. 3 and 4 

 show that a similar relation between the controls and the hypophysis- 

 fed animals has persisted up to the day that the animals reached an 

 age of 132 weeks. Fig. 3 shows the worm-fed controls of Experiment 1 

 at an age of 132 weeks. Fig. 4 the hypophysis-fed male (the female 

 died) at the same age. Comparison of the photographs as well as 

 of the figures for size and weight demonstrates that the hypophysis- 

 fed animal is still by far the largest one. 



A second experiment gave the same result. Fig. 5 shows the con- 

 trols of Experiment 2 ; Fig. 6, the hypophysis-fed animals of the same 

 experiment at an age of 88 weeks. Again the hypophysis-fed animals 



> Uhlcnhuth. E.. /. Gen. Physiol., 1920-21, iii, 347 



321 



