470 J. A. BADERTSCHER 



tissue cells is interesting in that its transformation to the free 

 cell can be easily followed. Now and then a transformed mesen- 

 chymal cell, d, can be found, the cytoplasm of which is quite 

 pale, being no more or only slightly more basophilic than that 

 in the ordinary connective tissue cells. Its cytoplasm, how- 

 ever, is homogeneous and its nuclear structure similar to that of 

 ordinary large lymphocytes. This type of cells evidently has 

 the power to wander about in the mesenchyme for occasionally 

 (very seldom) can one be seen in the epithelial anlage of the thy- 

 mus (fig 2, lower border to the left). These were observed 

 by Maximow who claims that their cytoplasm soon turns baso- 

 philic after they are formed. Judging from their structure 

 and the small number present his interpretation is correct and 

 they must therefore be considered as belonging to the same 

 type of cells as those in which the cytoplasm is more basophilic. 

 In some transforming mesenchymal cells, c, the cytoplasm be- 

 comes basophilic and the chromatin increases in amount while 

 the protoplasmic processes are being retracted, i.e., the cyto- 

 plasmic and nuclear changes take place simultaneously. This 

 process results in the formation of a cell in which the cytoplasm 

 is less basophilic and the nucleus contains less coarse granules 

 than in a fully developed large lymphocyte. These cells (young 

 lymphocytes) transform into the typical large lymphocytes as 

 represented in diagram e. Since this type of cells is of more 

 frequent occurrence than those represented in diagrams b and 

 d it is assumed that this is the most usual manner by which 

 a mesenchymal cell transforms into a lymphocyte. The type 

 of cells under consideration and represented in diagrams 

 c, d and e are the primitive mesamoeboids of Minot and the 

 primary wandering cells of Maximow and others. With Max- 

 imow and others, I agree that they are essentially identical 

 with the large Ijanphocytes which term was given them in the 

 account of the histogenesis of the thymus in the early stages 

 of its development. 



The power of the lymphocytes to develop in different directions 

 is clearly manifested in the interlobular septa of this stage in 

 which many lymphocytes of all types are found. Judging 



