109 
The thallus has been shewn to be diploid in every case 
in which division stages of the somatic nuclei have been 
obtained. The diploid number has been indicated for the 
thallus of the small winter form as well as for the large 
summer form. The plurilocular sporangia are diploid 
throughout their history and give rise to diploid zoids. The 
unilocular sporangia are the seat of reduction division and 
_ release haploid zoids which function as gametes and thus 
give rise to diploid thalli once more. Culture of the zygotes 
has shewn that the first stage of germination is an ecto- 
carpoid filament on which may arise plurilocular sporangia. 
The zoids released from such sporangia give rise to other 
filaments similar to the first. These may continue to 
reproduce by plurilocular sporangia until eventually a series 
of branches from the creeping filaments give rise to upright 
threads shewing early signs of longitudinal division and 
ultimately developing into recognisable As#erococcus 
plants. These plants have been successfully grown in 
cultures and have produced unilocular sporangia. The 
intermediate ectocarpoid filament stage is to be interpreted 
in the light of Professor Sauvageau’s culture experiments 
as a pléthysmothalle—an interpolated phase of microscopical 
dimensions maintaining a succession of individuals by zoids 
from plurilocular sporangia until such time as conditions 
permitted the establishment of the macroscopic plant. 
Many of the zoids released from the unilocular sporangia 
donot shew fusion but germinate at once into an ectocarpoid 
filament. The latter in its turn produces plurilocular 
sporangia which release haploid zoids. These behave as 
gametes and by their fusion reinstate the diploid con- 
dition and give rise to a diploid filament which may produce 
diploid plurilocular sporangia or give rise to plantules of 
Asperococcus. This provides a variant of the life-cycle. 
Both alternatives are indicated in the accompanying 
diagram of the life-cycle. 
