414 



BENNET M. ALLEN. 



any notable increase of colloid in the thyroid gland. Two were 

 preserved intact for demonstration purposes. Only eight out 

 of the twelve tadpoles sectioned were found to be in a satisfactory 

 state of preservation for histological study. This was due to 

 the fact that the tadpoles were usually preserved after they had 

 died. Although the aquaria were frequently examined, the 

 summer heat often caused considerable disintegration of the 

 thyroid gland before the specimens could be preserved. An 

 examination of Table VII. shows the length, width and thickness 



TABLE VIII. 



SIZE OF THYROID GLANDS AND COLLOID MASSES OF PITUITARYLESS Bufo TADPOLES 



NORMAL FEEDING AS CONTROLS: 



of each thyroid gland. The specimens are designated the same 

 as in Table I. From the dimensions of each gland was cal- 

 culated the volume of a parallelepiped that would contain it. 

 This of course would constitute but a rough relative approxima- 

 tion to the volume. Table VIII. shows similar measurements 

 and calculations made upon the thyroid glands of normally fed 

 pituitaryless Bufo tadpoles of size corresponding to these as 

 measured at the beginning of iodine feeding. A comparison of 

 Tables VI I. and VIII. will show that the thyroid glands taken as 



