358 



EXPERIMENTAL GIGANTISM 



while the average was 200.8 mm. From these data it seems that 

 while the largest specimen that could be found among eastern animals 

 of this species measured 208.7 mm., pathological conditions of the 

 endocrine system may produce giants of a maximum size of 280 mm. 



The Growth of the Hypophysis-Fed Animals. 



Experiment 1. — Of four normal metamorphosed specimens (Series 

 XIV) of Amby stoma opacum which had been reared in the laboratory 

 from eggs of the same female (Brood 1918) two were started on a diet 

 of anterior lobe of cattle hypophysis at an age of 60 weeks, i.e. at the 

 beginning of the third period of growth; the other two animals were 

 controls and were kept on an abundant diet of earthworms. The 

 size of the animals at- the beginning of the experiment may be seen 

 from Table I. 



TABLE I. 



The rate of growth of the anterior lobe-fed animals, after 2 weeks 

 of feeding, rose over that of the controls and continued at such a height 

 as is usually observed only in the second period of growth (Fig. 2). 

 The two control animals, although they were fed on an abundant diet, 

 continued to grow at a slow rate (Fig. 2) characteristic of the third 

 period of growth (Fig. 1). In consequence of their rapid growth the 

 anterior lobe-fed animals, 12 weeks after the beginning of the experi- 

 ment, had reached a size exceeding that of the largest animals of this 

 species on record (Table I, 72 weeks). At the end of the experiments 

 (caused by the death of the animals) the largest anterior lobe-fed 

 animal measured 138 mm., the smaller one 130 mm., while the controls 

 had reached a size of only 115 and 108 mm. respectively. Unfortu- 



