THYROID REMOVAL IN LARVAE OF RANA PIPIENS 



505 



and control tadpoles were alike distorted. The tadpole with the 

 straight est tail was killed on February 7. The body measured 

 43 mm. and the length of the tail was 80 mm. It is thus seen 

 that this tadpole had reached the gigantic length of 123 mm. 

 The shape of the head in front of the eyes undergoes marked 

 change in the thyroidless tadpoles. This can be well seen in the 

 outline drawings made to scale text figure 3. The exact nature 

 of this modification has not yet been worked out but it is a very 

 obvious change. It consists in a lengthening and broadening of 

 this region. 



In a number of tadpoles measurements of the alimentary 

 tract were made as given in table 1 : 



TABLE 1 



Measurements of alimentary tract 



DATE KILLED 



BODY LENGTH 



STOMACH 

 LENGTH 



KM VI.L 



INTESTINE 



LENGTH 



LARGE 



INTESTINE 



LENGTH 



COMBINED 



LENGTH 



STOMACH TO 



ANUS 



Controls 



August 6, no. 3. 

 July 25 



July 25... 



July 26. . . 

 Unknown . 

 Unknown . 



21.7 



24 body 

 59 total 

 22 body 

 29 total 

 23 

 25 



mm. 



34.5 

 95 



32 



27 

 35 

 29 



Thyroidless 



August 6, no.' 

 August 6, no. 

 October 12 . . . 

 December 6. . 

 December 15. 

 February 7. . . 

 February 14. . 

 February 22. . 

 March 6 



15.5 



29 



30 



27 



33 



43 



34 



34 



40 



208 

 301 

 237 

 190 

 207 

 426 

 164 

 288 

 261 



Attempted removal, failure 



August 6, no. 4. 



21.5 



13 



27 



46 



