476 , J. A. BADERTSCHER 



('06); (2) The lymphocytes can be regarded as undifferentiated 

 blood-cells and under certain conditions are, in some organs, 

 potentially like the primitive blood-cells, and (3) The like poten- 

 tiality of the lymphocytes in both the thymus and the mesen- 

 chyme is additional evidence that the lymphocytes first present 

 in the thymus have migrated into it from the mesenchyme. 



Whether or not any of the erythrocytes formed in the thymus 

 or in the mesenchyme surrounding it enter the circulation is 

 difficult to determine in fixed material. Some undoubtedly un- 

 dergo degeneration. In the mesenchyme of early stages and 

 in the interlobular septa of later developmental stages some 

 erythrocytes are present the cytoplasm of which is granular in- 

 stead of homogeneous. In some cells the granules are small, 

 round, and of a quite uniform size while in others the granules 

 vary greatly in size. Some are apparently about to break up 

 into a small number of irregularly shaped fragments. I am 

 confident that these erythrocytes are degenerating forms and 

 are not artifacts, for in the same microscopic field may be found 

 numerous other cellular elements (connective tissue cells, lym- 

 phocytes, nucleated and non-nucleated red cells) all of which 

 have the appearance of a good preservation. Also not infre- 

 quently erythrocytes can be found that have completely fallen 

 to pieces, the debris of degeneration being in the form of vary- 

 ing sized globules and irregularly shaped fragments, or irregular 

 groups or long drawn out rows of small deeply red stained (eosino- 

 phile) granules. The latter may be derived directly from the 

 disintegration of granular erythrocytes or from the further dis- 

 integration of large fragments of them. Some of the red cells 

 undergo degeneration while still in the normoblast stage. These 

 are characterized by a pyknotic nucleus and more or less gran- 

 ular cytoplasm. Except for their small size and the type of 

 nucleus they contain, some could easily be mistaken for small 

 eosinophile cells. 



Degeneration of some of the free erythrocytes in the lobules 

 of the thymus takes place in a manner similar to that described 

 above. Groups of free eosinophile granules can be found in 

 the thymus of all developmental stages in which red blood-cells 



