604 JAMES B. ROGERS 



Thymus glands of recently metamorphosed frogs 



42 Left thymus gland. 43 Right thymus gland, control 11 



44 Left thymus gland. 45 Right thymus gland, control 12 



46 Left thymus gland. 47 Right thymus gland, control 13 



48 Left thymus gland. 49 Right thymus gland, control 14 



50 Left thymus gland. 51 Right thymus gland, control 15 



52 Left thymus gland. 53 Right thymus gland, control 16 



Thymus glands of sexually mature young frogs 



54 Left thymus gland. 55 Right thymus gland, control 18 



56 Right thymus gland, control 19 



57 Left thymus gland. 58 Right thymus gland, control 20 



59 Left thymus gland. control 21 



60 Left thymus gland. 61 Right thymus gland, control 23 

 62 Left thymus gland. 63 Right thymus gland, control 24 



