EDUARD UHLENHUTH 349 



of 12 weeks. In experiments in which the chicks were fed anterior lobe 

 from an early stage, Wulzen^ succeeded in raising one anterior lobe-fed 

 cock which weighed 1,882 gm. as against the weight of only 1,597 gm. 

 of the control animal; no normal cock raised by Wulzen grew to the size 

 of the hypophysis-fed bird. Wulzen, however, raised only one cock 

 of this kind; moreover, no records are given in the paper as to the 

 normal maximum size of that race of chickens, and, therefore, it is 

 not certain that this cock could be actually considered a true giant. 

 From the experiments to be reported in this paper, it will become 

 evident that at least in one group of cold blooded animals, namely in 

 salamanders, feeding of anterior lobe leads to the attainment of a size 

 considerably in excess of not only the normal "average" size, but of 

 even the greatest known size of the two species {Ambystoma opacum 

 and Ambystoma tigrinum) employed in these experiments. 



Critical Remarks Concerning- the Methods of Feeding. 



It is usually stated that in order to obtain reliable results in feeding 

 experiments of this kind, only small amounts of the glandular pro- 

 duct should be added to an otherwise normal diet. I, however, am 

 of the opinion that this method, although considered at present as 

 the standard method, cannot, at least under all conditions, give con- 

 clusive results. It is possible that a gland may contain a specific 

 growth-promoting principle and yet may not give, with the above 

 mentioned method, positive results if the amount of the hormone fed 

 is too small. We do not know how much of a supposedly hormonic 

 substance is contained in a definite amount of the fresh product, nor 

 do we know how much of it may be required to produce gigantism or 

 accelerated growth. While most hormones act in small quantities, it 

 would be premature to conclude that all hormones should act in small 

 amounts. The main point in experiments of this kind is to be able 

 to prove that the control animals are fed in such a way as to show the 

 maximal rate of normal growth known to exist in the species experi- 

 mented upon. 



In my experiments the controls were fed exclusively the normal 

 diet, while the experimental animals were fed exclusively on the an- 

 terior lobes of the hypophysis of cattle. This method is based on the 



