34 GEORGE T. HARGITT 



growth; in the former, the nuclei of the accessory cells govern the 

 growth of the egg, and the nucleus of the egg is inactive till it 

 enters upon the prophase of maturation mitoses. 



A brief survey is sufficient to demonstrate a great variation in 

 the relative size of nuclei in coelenterate eggs, and I have under- 

 taken to test Jorgensen's suggestion. Figures 16 to 30 are the 

 outlines of a number of eggs with their nuclei, accurately drawn 

 to the same scale, all representing eggs at the end of the growth 

 period before the prophase of maturation mitoses. Figure 15 

 is a similar representation of a starfish egg of the same stage, 

 introduced for the sake of comparison. In the accompanying 

 table these eggs are arranged in order, the one with the relatively 

 largest nucleus heading the list. Since the nuclei are not always 

 perfect spheres, and the eggs depart even more from a true 

 spherical form, the figures given in the table for the diameters 

 are averages of the greatest and least diameter of both struc- 

 tures. The measurements, in millimeters, were made from pro- 

 jected images; if each average is multiplied by 1000 and divided 

 by 137 (the magnification of the 'projected images) the results 

 will give the average diameters in microns. From these 



diameter of egg . 



measurements was obtained the ratio — ; mdi- 



diameter oi nucleus 



cated in the third column. The figures of this column, squared, 



surface area of egg 



give the ratio , and the same figures, 



surface area of nucleus 



volume of egg 



cubed, furmsh the ratio ; (this computation is 



volume of nucleus 



given in the last column of the table). The actual volumes are 



not important, the relative volumes being the thing desired. 



Some inaccuracies result from the computations based upon 



formulae for surface and volume of true spheres, but it is believed 



these are not great enough seriously to disturb the order given 



in the table. These figures also represent measurements and 



ratios for particular eggs, and are not of the nature of constants; 



there is variation in size of eggs of the same species, but this, 



again, is not of such magnitude as to modify the table greatly. 



