FEEDING EXPERIMENTS ON TADPOLES 



461 



The next three experiments to be devscribed were performed 

 for the purpose of studying the influence of a mixed diet on 

 growth and development. One kind of food was gi\'en one day 

 and another the next. Previously the animals had been fed for 

 a considerable length of time on one kind of tissue and were then 

 transferred to another. 



Experiments VIII and IX consider a thyroid-thymus diet only. 

 The tadpoles of Experiment VIII had been fed on muscle before 

 the thyroid-thymus treatment began, while those of Experiment 

 IX had starved. It may be well at present to record the notes 



June 18. 



June 19. 



June 25. 



July 



TABLE 12 



Measurements in millimeters and diary notes 



21 .0-28 .0 



8.5-10.5 

 13.0-19.0 



4.5- 6.0 

 Hind legs appear 

 20.0-24.0 



7.0-8.0 

 12.0-16.0 



4.5- 5.5 

 The frog shape is noticeable 

 14.0-24.0 



5.5- 8.0 



9 .0-16 .0 



3.5- 5.0 



Very active; legs are very thin (fig. 2 m), but much better de- 

 veloped than in thyroid (Experiment IV, fig. 4 p). Length 

 of the hind legs 2.5 to 3.5 mm; the abdomen is bloated. 

 About 50% die 

 14.0-22.0 



5.5- 7.5 



8.5-14.5 



3.5- 5.0 

 Fore legs appear 10 days later than in the all-thyroid group 



(Experiment IV). 

 14.0-20.0 



5.5- 7.5 



8.5-12.5 



3 .5- 4 .5 

 Last ones preserved 



