96 



PIGMENTARY GROWTH AFTER ABLATION OF 



lations involved in the technical treatment. Be the explanation 

 as it may, it is certain that in the preparations the chromaffin 

 tissue of the normal animal almost invariably does not fill the 

 intracortical space accorded it. 



A duplication in wax of the volume of the medulla (x 187.5) 

 has been made for each of the three types of animal. In the 

 normal and thyroidectomized animals the total intracortical 

 medullary space has been included. It is evident, then, that if 



' The length of the component parts of the tadpole is given in the following order: 

 Total /Hind/Fore 

 Body /Tail/legs /legs 



only the actual chromaffin tissue exclusive of the surrounding 

 spaces had been drawn, an undertaking too laborious and uncer- 

 tain to be considered, the mass of the model in the normal and 

 thyroidless larvae would have been considerably reduced. From 

 the included table it will be seen that the volume of the medulla 

 while not seriously out of proportion to the size of the specimens 

 would appear to be increased in both the albino and the thyroid- 

 less larvae (table 10). 



Attention has already been repeatedly called to the incom- 

 pletely hypophysectomized tadpole, the so-called 'partial' albino, 



