Albert C. Eycleshynier 



301 



throughout, nor always cylindrical, it has been assumed that they repre- 

 sent perfect cylinders. The results obtained will be far from exact, yet 

 they must represent approximately the relative conditions. Moreover, 

 it may be said that no other cells in the body are more regular or admit 

 of more precise measurement. In determining the relative volume of 

 cytoplasmic to nuclear material I have used the following formula : 



The above computations show interesting changes in the relative vol- 

 umes of cytoplasmic and nuclear material during growth. In the 8 mm. 

 embryo a unit of nuclear material is correlated with two to three units 

 of cytoplasm; in the 17-26 mm. embryo with five to seven units of cyto- 

 plasm; in the adult with twenty to thirty units of cytoplasm. In other 

 words, as the embryo approaches the adult condition there is a progres- 

 sive increase in the amount of cytoplasmic material with the end result 

 that there is twenty to thirty times as much cytoplasm in physiological 

 equilibrium with a given quantity of nuclear material as in the earlier 

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