SECT. 2] 



AND WEIGHT 



391 



found that his series of chick embryo-weights could be accurately 

 described by the equation: 



T3-6 



1-496' 



or W=KT^-\ 

 where K = o-668. 



This was not unlike the Balthazard-Dervieux formula for the 

 human embryo: 



T= 19-4 X \^W. 



23 

 Diojs 5 



10 U t2 13 14 



Incub&lion 2052 

 Fig- 37- 



Murray plotted the log. wet weight against the incubation age, and 

 obtained a curve concave to the abscissa (see Fig. 37) corresponding 

 to the curve which McDowell, Allen & McDowell got for the mouse 

 embryo (see Fig. 22). He also found that the relation of log. weight 

 to log. age was a straight line as far as his series of weighings went, 

 and showed that the weighings of Hasselbalch and of Lamson & 

 Edmond fell on the same straight line (Fig. 38). Murray's formula 

 gave very good agreement with his figures, but these did not extend 

 further back than the fifth day of incubation. When, later, Needham 



