No. 7 Ultraviolet photomicrograph of similar tumour cell in interphase, at 

 2750° A, by courtesy of the same authors. X 3300 (reduction 3/4). Notice the 

 presence in the nucleus of absorbing material other than the nucleoli, apparently 

 similar to the heterochromatic granules of embryonic mouse cells. [By courtesy, 

 J. Roy. Micr. Soc.) 



