586 
a group of four initial cells. The middlemost part of the disc projects and forms 
an upright frond which is first cylindrical, later vesicular, and the four apical cells 
become the first initial cells of the frond. In my cultures in the laboratory of 
marine biology at Frederikshavn in 1928 and 1929 the conditions were evidently 
also unfavourable to the germination, for most of the spores did not germinate, 
the divisions of the germinating spores were not regular, and the four initial cells 
could not be observed. After 7 or 8 days the germlings had the shape of discs or 
cushions with rhizoids issuing from the margin. The cell-divisions were more or 
less irregular, and sometimes 
portions of the original spore- 
cell did not take part in the 
divisions producing the germ- 
ling. A group of initial cells 
could not be detected, but the 
cells often showed a very appa- 
rent arrangement in rows, an 
evident proof of the presence 
of a meristeme (fig. 585). 
After 17 days the germ- 
lings had grown much larger, 
having usually an orbicular 
disc composed of radiating 
cell-filaments about 100 w in 
diameter and an upright frond 
of about the same length as 
the diameter of the disc. The 
Fig. 586. upright fronds were nearly 
Lomentaria clavellosa. Germlings found in Nature, growing on Polysi- eylindrical unbranched The 
phonia urceolata, Tonneberg Banke, northern Kattegat, July. A, B ER $ 
560:1, C, 200 : 1. characteristic structure of the 
apex could not be observed. 
Hairs were wanting (August 4th) (fig. 585 D). Germlings from the same culture a 
month and a half older had only reached a length of 150 to 224 w and did not 
show the normal structure, but their colour was normal. The fronds were often 
somewhat curved, sometimes showing incipient branching. Growing under better 
conditions, the germlings would probably have reached a larger size. 
Germlings were repeatedly met with in Nature in the months of July to Oc- 
tober, growing on various Algæ, as e.g. Polysiphonia, Desmarestia aculeata, leaves 
of Zostera or tests of Hydroids. They must have arisen from spores set free at the 
same season, and generally they agreed with the germlings obtained in the cultures. 
Those found in the middle of July reached a length of 0.2—0.3 mm (fig. 586), whereas 
germlings met with in August reached a length of 2 mm. The largest specimens 
of the young plants gathered in October reached in the various localities lengths 
