Lewis . — The Life History of Griffithsia Bornetiana . 683 
borne on the sexual plants sometimes germinate as monospores, though 
this can be ascertained only by cultivation. 
On the other hand, tetrasporic plants may at times produce structures 
morphologically identical with procarps. Text-fig. 1 is taken from a 
tetrasporic plant of Spermothamnion Turneri collected at Wood’s Hole 
in August, 1907, and shows tetraspores and 
procarp on opposite branches of the same fila- 
ment Text-fig. 2 shows a section of the 
tetrasporangium in which the definitive tetra- 
spores are formed, though not yet separated. 
Antheridia have not been reported as occurring 
on Spermothamnion Turneri at Wood’s Hole, 
and cystocarps are very rarely produced. 
Whether functional gametes are ever produced 
on an individual which bears normal tetraspores 
is not known. 
In Spermothamnion Turneri 1 from Helgoland, Pringsheim states 
( 63 , p. 26) that ‘ Kapselfriichte, Vierlingsfriichte und Antheridien normal 
zusammen auf denselben Exemplaren auftreten’. This case is obviously 
of so great theoretical interest that I took occasion, in the summer of 1908, 
to collect this plant at Helgoland. Hundreds of plants were collected, the 
great majority of which bore only tetraspores. In a few individuals 
1 The species called Spermothamnion roseolum by Pringsheim is stated by Professor Kuckuck 
to be identical with S. Turneri. In this connexion I wish to offer my thanks to Professor Kuckuck 
for the privilege of working at the Biologische Anstalt at Helgoland, 
