466 
P. Kuckuck, 1894, Bemerkungen zur marinen Algenvegetation von Helgoland. (I). Wissensch. Meeres- 
untersuch. Neue Folge. I. Band. 
W. NIENBURG, 1908, Zur Keimungs- und Wachstumsgeschichte der Delesseriaceen. Botan. Zeitung 1908, 
p. 183, Taf. VII. 
R. W. Paırrıps 1898, The Development of the Cystocarp in Rhodymeniales: II. Delesseriaceae. Annals 
of Botany, Vol. 12. 
N. WILLE, 1885, Bidrag til Algernes physiologiske Anatomi. K. Sv. Vet. Akad. Handl. Bd. 21 No. 12. 
Stockholm. 
— , 1887, Beiträge z. Entwickelungsgeschichte der physiolog. Gewebesysteme bei einiger Florideen. N. A 
Leop. Car. Ak. Bd. LII Nr. 2. Halle. 
See further p. 297 and p. 402. 
My investigations on the Danish Delesseriaceæ, which have been directed to the 
structure and development of the frond, were almost finished when I received Kyrın’s 
important paper (1923) which contributes so much to the morphology of this family. 
My observations are in full accordance with those of Kyrın to which I can, however, 
give some additions. Two matters only must here be emphasized. 
1. The presence of secondary pits, first pointed out by me (1888) in Mem- 
branoptera alata, was ascertained in all the species in question, both in the ribs 
and in the monostromatic frond. In the mid-ribs of the fronds multiple pits occur 
in the transverse walls of most of the long cells. These pits are in most cases all 
of secondary kind, arising at different moments between two pericentral or similar 
cells that were not before-hand connected by pits. In Phycodrys rubens, however, 
secondary pits are alsc formed between the cells of the axial cell-row, though these 
cells are from the first connected by a primary pit. The secondary pits are here 
formed in the periphery of the wall while the primary pit is central (figs. 429, 430). 
2. The germination has only been observed in Apoglossum ruscifolium by TOBLER, 
but young specimens of the other species were found in nature. In Apoglossum rus- 
cifolium, Delesseria sanguinea and Membranoptera alata the primary axis of the plantlet 
becomes a typical frond provided with a mid-rib. In Delesseria sanguinea this prim- 
ary frond seems to obtain only a moderate length, but in Membranoptera alata and 
probably also in Apoglossum ruscifolium it becomes the main axis of the frond, and 
in Membranoptera it early begins branching. In Phycodrys rubens, on the other hand, 
the primary axis of the young plant develops into a thorough monostromatic frond 
without mid-rib, reaching only a length of half a cm or a little more; the typical 
fronds arise as adventitious shoots from the stalk of the primary shoot. The accord- 
ance of this primary frond with the normal frond in Nitophyllum corroborates the 
opinion put forth by earlier authors, in particular by Kyrın, that this species must 
be referred to the Nitophyllee. 
