Hazen: Lire History oF SPHAERELLA LACUSTRIS 239 
Haematococcus Cordae Meneghini. Mem. R. Accad. Sci. di Tor. II. 
S300 3a6 
Haematococcus pluvialis Flotow. Nov. Act. Acad. Caes. 20’: 413- 
606. 1844. Sachs ('76, ’87), Cohn (781, '82), Bütschli ('84), 
Parker (^93), Zopf (’95). 
Protococcus pluvials Kützing. Phyc. Germ. 146. 1845. Tab. Phyc. 
1: 2. 1849. Cohn (’50), White (’80), Gibson (’89), Bennett 
and Murray (’89), Huxley and Martin (’92). 
Protosphaeria pluvialis Trevisan. Atti Congr. Sci. Ital. in Ven. 28. 
1848. 
Protosphaeria Cordae Trevisan. Atti Congr. Sci. Ital. in Ven. 28. 
48. 
Chlamydococcus epi Al. Braun. Betracht. über die Erschein. d. 
Verjüng. in d. Nat. 219. 1851. Cohn (^52, ' 54, '67), Pritchard 
(^61), Sehr (768), Velten (’71), Rostafinski (’71), Stein 
(^78), Kirchner, Krypt.-Flor. Schles. 1878. Wolle, Fresh-Water 
Alg. U. S. 164. 1887. Cooke, Brit. Fresh-Water Alg. 51. 1882. 
Demetzky (83), De Toni and Levi, Flor. Alg. Ven. 1888. Dan- 
geard ('88). 
Hysginum pluviale Perty. Zur Kentn. kleinst. Lebensf. 87-95. 1852. 
Haematococcus lacustris (Girod) Rostafinski. Mem. Soc. Nat. Sci. 
9: rdo. 1875. De Joni ( 39), Chodat ( g6, 
97), Phyc. Bor. Am. No. 114. 1895. Bütschli ('84, PZ 45). 
Shun pluvialis (Flot.) Wittrock. Wittr. and Nordst. Alg. Exsic. 
233. 1886. Wille; Engler and Prantl, Die nat. Pflanz. 1°: 
390 1997, 
Sphaerella lacustris (Girod) Wittrock. Arch. d. Nat. Land. v. Bohm. 
e". 1888. 
SUMMARY 
A. Life History 
I. THE ORDINARY CYCLE OF DEVELOPMENT 
. The normal resting-cell forms by endogenous division four, 
dne or sixteen daughter-cells. 
2a. Under unfavorable conditions these daughter-cells remain 
in the resting condition and return to stage I. 
26. Under favorable conditions these daughter-cells escape 
from the mother-cell-wall as free-swimming megazooids, which 
may while motile grow to four times their original size. - 
