EXTIRPATION OF ANTERIOR LOBE OF HYPOPHYSIS. 125 



(a) 16 tadpoles were cut along a plane lying just above the 

 hypophysis ingrowth. In the majority of cases the brain was 

 touched. 4 died on May 5. 



(&) 15 tadpoles were cut in the usual manner in preparation 

 for removal of the hypophysis ingrowth but as in the preceding 

 (a) the hypophysis ingrowth itself was left intact. 



After (a) and (6) had been kept separate for 10 days with the 

 loss of 4 in (a) they were then combined. 



Following this, deaths occurred as follows: 



May 18 i dead 



21 i " 



"24 2 " 



" 25 5 " 



" 25-June 9 6 " 



Thus on June 9 14 were still living and healthy. They were 

 then killed. It is interesting to compare the results obtained 

 here with those found in the above table. It is seen that by de- 

 ducting the 4 that died in the first 5 days, as a result of serious 

 injury there were 28 that had a good start without any mortality 

 until May 18; 14 or \ of these survived 40 days later. Unfortu- 

 nately a study of the mouths of these tadpoles was not made. If 

 it had been done it might have been possible to explain some of 

 this mortality as a result of starvation due to imperfect mouth 

 development resulting from injury. A series of measurements 

 made on May 16 showed 12 to be below 11.5 mm. in length while 

 the maximum length was 13.6 mm. The very smallest, 8.7 mm., 

 was of a silvery color due supposedly to the accidental removal 

 or injury of the hypophysis ingrowth. 



This leads to the important point that this was the only case 

 of a color change in the 28 specimens, thus showing that the ab- 

 sence of the hypophysis and not the mere wound itself is the 

 cause of the color change. Along this line may be mentioned 

 that in nearly every experiment where removal of the hypophysis 

 was practiced one or two operated tadpoles failed to show the 

 color change characteristic of the others. Several of these were 

 sectioned and in each case it was found that there had been failure 

 to remove the hypophysis. There is thus no doubt whatever 

 that the absence of this gland is the cause of it. The nature of 



