92 THE AMERICAN ARBACIA 



sene, and other metal-chelating agents extend the functional Ufe span 

 very greatly. For Lytechinus pictus and S. purpuratus see Tyler and 

 Atkinson (1950). 



e. Injury 



Arbacia sperm are injured by hypo- and hypertonic sea water; alcohol 

 1-12% added to sea water; sea water slightly acidified with HCl; 

 ageing for 6-24 hours (Dungay, 191 3). The injured sperm caused 

 irregular cleavage, abnormal blastulae, gastrulae and plutei, the results 

 being non-specific. The sperm are also harmed by CuCla and HgClg 

 (F. R. Lillie, 1921b). 



f. Agglutination 



A very noticeable phenomenon in motile Arbacia sperm is agglutina- 

 tion, the collection of numbers of sperm into clumps. This was ob- 

 served by Buller (1900b) in A. lixula sperm, and has been studied in- 

 tensively in A. punctulata by F. R. LiUie (1912, 1913a, b, 1914, 1915a, 

 1919, p. 112, etc.); and by Glaser (1914b); Cohn (1918); Woodward 

 (1918); Sampson (1922); Popa (1927); et al. The substance in sus- 

 pensions of eggs causing this reaction has been called by F. R. Lillie 

 {\(^\'j,2i) fertilizin and earlier was called iso-agglutinin{Y. 'K.'LilYic, 191 2). 

 Sperm extracts agglutinate the eggs and inactivate fertilizin (Frank, 

 1939). The agglutination is usually between the heads of the sperma- 

 tozoa (F. R. LiUie, 1919, p. 119; Sampson, 1922; Tyler, 1948). Sec 

 Part IV, Fertilizin and Agglutinin for recent reviews, especially Tyler 

 (1948, 1949 c). 



g. Chemotaxis 



The classical studies of Pfeffer (1884) showed without much question 

 that the sperm (antherozoids) of ferns were attracted to the archego- 

 nium (and egg), and that this was due to the mafic acid and its salts 

 occurring there, a definite chemotaxis. But whether the sperm of 

 animals are attracted to the eggs by chemotaxis has never been proven. 

 Buller (1900 a, b, 1902), working in Pfeflfer's laboratory, confirmed 

 the chemotaxis in the case of ferns, but when working on sea urchins, 

 including Arbacia lixula, at Naples, could find no evidence of chemotaxis, 

 and concluded that in these forms the eggs and sperm meet by chance. 

 Other investigators (e.g. von Dungern, 1902) confirmed Buller's re- 



