470 
long time as a triangular projection, after the entrance of the nucleus in the receiy- 
ing cell (fig. 431). No wall separating two cells in the monostromatic part of the 
leaf contains more than one pit. 
The shape of the frond is rather variable according to 
the different length and breadth of the lobes and to the differ- 
ent manner in which the growth recommences after the rest 
of the winter. In some cases a number of the lobes resume the 
growth from a broad base and form new leaves as prolong- 
ations of the lobes of the old leaf. In other cases the apical 
cells of the lobes give rise to a leafy shoot with a narrow 
stipe, and it has then a similar character to the other mar- 
ginal shoots arising from single marginal cells, probably prin- 
Fig. 432. cipally from initial cells of the third order. Most of these shoots, 
Phycodrys rubens. Multicell- SL a 2 
asien ED which may be very numerous, reach only a small size and 
become fertile. Adventitious shoots may also arise, in older 
leaves, from the middle-rib and from the side-ribs. KyLiN found tetrasporiferous 
leaflets projecting from the veins (1923 p. 65); I found the same. Long narrow shoots 
are frequently produced, mostly at the 
base of the plants, but sometimes also 
from the upper end of the shoots. They 
often bear multicellular papillæ (fig. 
432) which take the function of hapters 
when meeting a firm substratum, f. 
inst. other Algæ. Such papillæ, which 
have first been described by P. Mac- 
Nus (l.c. p. 75), occur frequently in 
this species, also in the broader forms 
of the frond and frequently cause the 
fronds to be entangled with each 
other and with other Algæ. 
Germinating spores have not been 
observed in cultures, but young plants 
have repeatedly been found in nature, 
principally in hydroids. The small 
plant shown in fig. 433 A is most pro- 
bably a sporeling of Phycodrys rubens, 
as it has been found by dredging in 
April in company with adult specimens 
of this species while other species of 
Delesseriaceæ were not present. This Fig. 433. 
young plant shows much resemblance Pfycodrys rubens. A sporeling found in April off Refsnæs 
2 ae (Store Belt). 270: 1. B plantlet found in July in the Little Belt 
to the sporelings of Nitophyllum punct- on Sertularia. 63 : 1. 
= 
ERA mA 
ETA 
