THE MATURE EGG, UNFERTILIZED AND FERTILIZED 85 



k. Diagrams of Surface Layers of Arbacia and other Eggs 



Chambers, 1938 b. Am. Nat. 72 : 146. Fertilized sea urchin egg. 



Dan and Dan, 1940. Biol. Bull. 78 : 488. FertiUzed Strongylocentrotus pul- 



cherrimus egg. 

 Danielli, 1942. Bourne^ s Cytology p. 69. FertiUzed Arbacia egg. 

 Kopac, 1940 a. Cold Spring Harbor Symp. 8 : 168. Unfertilized and fer- 

 tilized Arbacia egg. 



Moser, 1939.3. J. Exp. ^ool. 80 : 432. Unfertilized Arbacia egg. 

 Motomura, 1941b. Sci. Rep. Tohoku Imp. Univ. 16 : 355. Unfertilized 



eggs of S. pulcherrimus. 

 Ohman, 1945. Archiv f. ^ool. 36A, no. 7 : 39. Unfertilized sea urchin 



egg. 

 Runnstrom, 1949 a. Adv. Enzymol. 9 : 245; 1949 b. Pub. Staz. -^00/. Nap. 



21 : 13. Unfertilized sea urchin egg. 

 Runnstrom and Monne, 1945a. Arkiv f. ^ool. 36A, no. 18 : 2. Sea 



urchin oocyte. 



1. Granules 



Oil globules. 0.6 to i.o {i (spherical) (E. B. H.). 



Mitochondria. 0.6 to i.o [x (spherical) (E. B. H.). 



Yolk granules. 0.7 to i.i (x (irregular, polyhedral) (E. B. H.). 



Pigment vacuoles. All sizes up to 1.7 fx (spherical). Unevenly spaced 

 all through unfertilized tgg\ most go to periphery on fertilization 

 (McClendon, 1909b; E. B. Wilson, 1926, Fig. 2; Cannan, 1927; 

 E. B. H.; etal). 



Cortical granules. 0.8 \x (spherical). (Moser, 1939a; E. B. H., 1946a; 

 et al. At periphery in unfertilized eggs; disappear on fertilization. 



Microsomes. 0.4 y. or less (E. B. H.) Very small granules not visible 

 in normal living egg, but seen in the centrifuged egg throughout the 

 clear layer when stained with Heidenhain's haematoxylin. (Lyon, 

 1907; E. B. Harvey, 1940c; E. B. Wilson's 1925 The Cell p. 32). 



(Golgi bodies, described by E. B. Wilson (1926), but by no one else; 

 Just (1927) thinks they are oil drops). 



Percentage of formed bodies based on measurements in centrifuged 

 eggs (E. N. Harvey, 1932 a): 



Nucleus 0.4% 



Oil g obules i-0% 



Mitochondria 4-8% 



Yolk 27.2% 



