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('. M. JACKSON 





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Fig. 3 From a photograph of one lobe of the tliyroid ghuul from nonnal al- 

 bino rat No. S 5.3, age 74 days, gross body-weight 172 grams. Parathyroid in- 

 cluded. Compare with figures 4, 5 and 6, representing thyroids in rats of the 

 same age, Init held at maintenance from age of 3 weeks. (X 28.) 



Fig. 4 From a photograph of one lobe of the thyroid gland from albino rat 

 No. S 11.63, age 72 days, gross body-weight 23.8 grams (held at maintenance from 

 age of 3 weeks). Follicles much larger at perii)hery. Some extra-capsular tis- 

 .sue is iiicliKh'd. Parathyroid relatively large. (X 28.) 



