486 J. A. BADERTSCHER 



in embryos of about 180 mm. in length and are most numerous 

 in the parenchyma of the thymus of full term embryos. In 

 the interlobular septa they are seldom found in embryos from 

 65 to 85 mm. in length. They occur first in appreciably large 

 numbers in the septa of embryos of about 125 mm. in length 

 and are most numerous in embryos 165 to 185 mm. long but 

 are still present in the septa in full term embryos. 



I wish to thank Prof. B. F. Kingsbury for the aid and encour- 

 agement given me on this work, and Prof. S. H. Gage for many 

 suggestions. 



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