PLATE 6 



EXPLANATION OF FIGURES 



28 to 32 Involution of the so-called fat cells of the bone marrow to ' Riesen- 

 zellen' in the plasma medium. White bone-marrow of a younger well-fed, full- 

 grown chicken in tissue culture from November 30 to December 1, 1915. Con- 

 servation: Formol. Osmium, Safranin stain. 



118 



