OF EXPERIMENTAL WORK 225 



Immature Egg. — Is more viscous than mature. (Heilbrunn, 192 1, 1928, p. 278, 

 1943, p. 70; Goldforb, 1935b; E. B. H.). 



Maturation. — During, decrease in viscosity (Goldforb, 1935 b; E. B. H.). 



Fertilized Egg. — More viscous than unfertiHzed. (Heilbrunn, 1915, 1920a, 1928, 

 p. 264; E. B. Harvey 1932, 1933b). 



Prophase. — After breaking of nuclear membrane, increase (E. B. H.). 



Parthenogenetic Egg. — More viscous than unfertilized. (Heilbrunn, 191 5, 1928, p. 261). 



Stages in Mitosis. — Changes in viscosity (Heilbrunn, 1920a, 1921, 1927, 1928, 

 p. 265, 1943, p. 653; Chambers, 1919, 1924; Fry and Parks, 1934; Fry, 1936; 

 Page, 1929 a). 



Red Halves. — More viscous than white halves (E. B. Harvey, 1932; Chambers, 

 1938a). 



Decrease in Viscosity by 



Ageing. Decrease after 35 hours (Goldforb, 1935b). 



Alkalies (Barth, 1929). 



Anaesthetics. Ether (Heilbrunn, 1920a and b, 1925c, 1927, 1928, p. 205, 288; 

 see Chambers, below under Increase). Ether and other anaesthetics (Heilbrunn, 

 1920a and b, 1928, p. 206). See Table 15. 



Carbon dioxide (Howard, 1931, 1932; Jacobs, 1922, after short exposure). 



Colchicine (Beams and Evans, 1940, prevents gelation and aster disappears after 

 fertilization; Wilbur, 1940). 



Electric current; direct and alternating; transitory decrease, then increase 

 (Angerer, 1939). 



Fatty acids and salts of fatty acids (Howard, 193 1). 



Heparin and heparin-like substances (Heilbrunn and Kelly, 1950). 



Hypotonic sea water (Heilbrunn, 1920a and b, 1928, p. 211; Chambers, 1924; 

 E. B. Harvey, 1943). 



Mechanical agitation (Chambers, 1924). 



Nitrogen mustards (E. B. H. and Cannan, unpub.). 



Pressure, hydrostatic; on unfertilized eggs and on cortex of fertilized eggs (Brown, 

 1934; Marsland, 1938, 1939, 1942, 1950, 1951.) 



Salts. CaClj (Heilbrunn, 1923, 1927, 1928, p. 146, 1943, p. 81; E. B. Harvey, 

 1945; see Chambers, 1949). MgClj (Ibid). Aluminum chloride (Heilbrunn, 1925b, 

 1928, p. i5'i). Copper chloride; latent period 21 min, then decrease, then increase 

 (Angerer, 1937). (See also Heilbrunn, 1928, p. 143). 



Temperature. Heat, decreasing viscosity with increasing temperature — 1.8 "C. 

 to +28 °C (Costello, 1934). Cold, about — 3 °C (Heilbrunn, 1920a and b, 1928, 

 p. 106). Eggs stratify by gravity if kept overnight at 8"^ but not at 21.5". They break 

 more readily on centrifuging at low temperatures (E. B. H.) ; Costello (1938) found 

 the reverse. 



Ultraviolet rays, decrease at first, then increase. (Heilbrunn and Young, 1930). 



Increase in Viscosity by 



Acids (Barth, 1929; list of acids and effective pH on p. 510). 



Ageing. Viscosity increases for first 35 hrs., then decreases (Goldforb, 1935 b). 



Anaesthetics. Chloretone (Heilbrunn, 1920a, b). Ether (Chambers, 1924; see 

 Heilbrunn and above under Decrease). 



Body fluid (Goldforb, 1935 b). 



Carbon dioxide (Jacobs, 1922 after long exposure). 



Cytolysis (Heilbrunn, 1928, p. 245). 



Electric current; direct and alternating; transitory decrease, then increase (Ange- 

 rer, 1939). 



Formalin (Heilbrunn, 1927). 



Hypertonic sea water (Heilbrunn, 1915, 1920a, 1943, p. 81; Chambers, 1924; 

 E. B. Harvey, 1943). 



