THE SIZE OF ORGANISMS 



189 



the protoplasm has been transformed into the contractile substance of 

 the fiagellum. 



I have not been able to measure the volume of muscle cells in 

 Crepidula, but such measurements have been made by Eycleshymer 16 

 for the striated muscle cells of Necturus. From the measurements 

 given by Eycleshymer, I have calculated the nucleus-plasma ratio in 

 the usual manner, i. e., by determining the ratio of the nuclear volume 

 to the cell volume less the nuclear volume ; and I find that in the 7 mm. 

 and 8 mm. embryos this ratio is about 1 :11, whereas in the 23 cm. 

 adult it is about 1 :73. The increase of cell substance is therefore less 

 than seven times, instead of twenty or thirty times, that of the nucleus, 

 as he states. 



Ratio of Nuclear Volume to Cell Volume in Adult Individuals of 



Crepidula plana 



Kindi of Cells 



Spermatocytes I 



Spermatocytes II 



Spermatids (chromatin con 



densed) 



Oocytes I (before yolk forma 



tion) 



Large ganglion cells (not in 



eluding any outgrowths).... 

 Ectodermal epithelium (of 



foot) 



Epithelium of mantle (near 



anus) 



Intestinal epithelium 



Gastric epithelium 



Branchial epithelium 



Liver cells (without secretion 



products) 



Liver cells (with secretion 



products) 



Oocytes I (before maturation 



and with maximum quantity 



of yolk) 



Maximum 



Diameter 



of Cell 



8 



7 



3 

 10 



17X17X23 

 6X 6X15 



5X 5X15 

 11X11X12 

 10X10X36 



7X 7X 9 



14X14X30 

 15X15X45 



150 



Maximum 

 Diameter 

 of Nucleus 



Volume of 

 Nucleus 



Cu. ja 



Volume of 

 Cell Less 



Volume of 



Nucleus 



Cu. m 



6 

 5 



113 



64.4 



155 

 114.6 



2 



4.18 



9.94 



6 



113 



407 



12 



905 



5724 



5 



65.4 



474.6 



4 

 6 

 8 

 4 



33 

 113 

 268 



33 



342 

 1339 

 3332 



408 



9 



382 



5498 



6* 



113 



10012 



42 



32409 



1722591 



Nucleus- 

 Cell Ratio 



1: 1.37 

 1: 1.7 



1: 2.38 



1: 3.6 



1: 6.a 



1: 7.1 



1:10.$ 



1:11.8 

 1:12.4 

 1:12.3 



1:14.4 



1:88.6 



1:53 



It is important to note that Eycleshymer found that as the fibrillaa 

 are progressively formed out of the protoplasm of the cell, the nuclei are 

 crowded out of the center of the cell toward its periphery; that the 

 nuclei become more densely chromatic, and especially so on the side of 

 the nucleus toward the fibrillar ; and that possibly the nuclei may disin- 

 tegrate and their chromatin go to form the dark bands of the striated 



18 Eycleshymer, "The Cytoplasmic and Nuclear Changes in the Striated 

 Muscle Cells of Necturus," Am. Jour. Anat., 3, 1904. 

 * Nucleus shrunken and irregular in shape. 



