E. HOFF-JORGENSEN 



acetone and 250 ml. of ether for 10 min. at slow speed. After standing for 10 min. the 

 acetone-ether was withdrawn and 300 ml. of ether added. After stirring for 5 min. 

 the suspension was filtered, washed with ether and dried in a desiccator over sul- 

 phuric acid. 



?L 36 



1 



^700 



^ 500 



\ 



<i 300 



K 



m 



--.-./ 



/ 2 3 9 s 



dous 





t 1 1 1 1 r 



2 f 6 8 /O /2 ft . /6 /8 

 Incubation, dot/s 



Figure 4. Content of DNA in eggs of the domestic fowl 

 during development of the embryo. 



Figure 4 shows that the content of DNA is the same until 3 days after incubation. 

 The average of 8 determinations of the content of DNA in unfertilized eggs 

 (5 0_ 55 g«) wa s 118 fig. per egg with a standard deviation of 12 /xg. Mirsky and Ris 

 ( : 949) found 2-34 x io~ 6 fig. DNA in erythrocytes and 2*39 x io~ 6 fig. DNA in 

 hepatic tissue per cell of the domestic fowl. If we take 2 37 X io~ 6 fig. DNA as 

 representing the DNA content of the diploid cells of the domestic fowl we get: 



DNA per esr? 118 



t^ ta F ~ = io 6 ~5 x io 7 



DNA per cell 237 



indicating that the egg contains enough DNA for 5 X io 7 diploid cells. 



DISCUSSION 



Hoff-Jorgensen and Zeuthen (1952) showed that in the egg of the frog most of the 

 DNA must be located in the cytoplasm and made available for the formation of new 



86 



