l6o ALPHABETICAL COMPILATION 



No Fading with Anaerobiosis {i.e. not reduced). — (Korr, 1939, p. 83 and Ball in same- 

 paper, p. 92). See under Echinochrome. 



Electric Charge. — Possibility of (E. N. Harvey 1909, 1910b; McClendon, 1910b, 

 1912a, Heilbrunn, 1926b). 



Contain Copper. — (Glaser, 1923). 



Other Species 



Fischel, 1906b. A. lixula. 



E. B. Harvey, 1933a, 1938a. A. lixula. 



CLEAR LAYER OF CENTRIFUGED EGGS 



Position in Arbacia. — Layer in centrifuged eggs between oil (centripetal) and granules : 

 mitochondria, yolk and pigment (centrifugal) ; contains nucleus (early investigators 

 Lyon, 1906 a, 1907; Morgan, 1909; McClendon, 1909 a et al.; later investigators 

 E. N. Harvey, 1932a; E. B. Harvey, 1932, 1936, 1940c, etc.; et al.). 



Structure. — Optically empty in living egg except after prolonged centrifuging. A 

 narrow band of granules then appears across the clear layer of white halves and clear 

 quarters, forming two zones (E. B. Harvey, 1946 a; McCulloch, 1952 a). Birefrin- 

 gent fibrils in lower part of clear zone (McCulloch, 1952 a). Electron microscope 

 preparations (McCulloch, 1952 a; Lansing, Hillier, and Rosenthal, 1952). Some 

 pigment granules remain in clear layer of eggs late in the season (E. B. H.). 



Amount. — 61. i % (E. N. Harvey, 1932a); 45% (Costello, 1939); these figures in- 

 clude fluid between the packed granules; the difference between the two figures is 

 probably due to the amount of centrifuging. About 2/3 of total fluid is in clear layer 

 (E. B. Harvey, 1946a). 



Specific Gravity. — About 1.0358; of whole egg is about 1.0485 (Heilbrunn, 1926 a). 



Viscosity. — Two centipoises, determined by centrifuge tests and return of granules 

 (Heilbrunn, 1952, p. 81 ; see also Heilbrunn, 1926a, b, 1927, 1928, p. 67). 



Stain. — With vital dyes. Faint stain with Bismark brown, chrysoidin, methyl 

 violet, neutral red, Nile blue, rhodamine, toluidin blue (E. B. Harvey, 1941 c). Two 

 portions stain differentially (E. B. Harvey, 1946 a). Table 8. 



Fixed material. — Layer is filled with very small granules which stain blue with iron 

 haematoxylin (Lyon, 1907; Morgan and Lyon, 1907; E. B. Harvey, 1940c; E. B. 

 Harvey and Lavin, 1944; et al.); these are probably the "microsomes" of Wilson 

 (1925, p. 32), they measure about 0.2 fx in diameter (E. B. H.). Clear layer stains 

 with protoplasmic stains, alum cochineal (Lyon, 1 907) . Stains differentially (two kinds 

 of material) with haematoxylin-orange-G-eosin (E. B. Harvey, 1946 a, Figs. 32, 33). 



Ultraviolet Light. — Absorbed by clear layer in formalin-fixed sections (E. B. Harvey 

 and Lavin, 1944). 



Localization of Peptidase. — In clear layer (Holter, 1936). 



Other Species 



In some other species, e.g., Sphaerechinus granularis, the clear layer is at the centripetal 

 pole as it is in Arbacia punctulata and A. lixula, being lighter than the granules. In other species, 

 e.g., Psammechinus microiuberculalus, it is below the yolk but above the mitochondria. In still 

 other species, e.g., Tripneustes esculentus, it is heneath the yolk and mitochondria, being the 

 heaviest material in the egg. In some species, e.g., Paracentrolus lividus, the clear material 

 may be in more than one zone (E. B. Harvey, 1933a, 1938a). 



Other references for clear layer: 

 Harvey, E. B. per E. N. Harvey, 1939. Echinarachnius parma, Strongylocentrotus drdbachiemis , etc. 

 Harvey, E. B., 1947. Lytechinus variegatus and other Bermuda forms. 



