696 
Yendo .— The Development of 
an elongation of an epidermal cell without any septum throughout the whole 
length. This is somewhat different from the case which Kutzing 1 has 
illustrated in Laminaria saccharina. Griggs 2 found tufts of filamentous 
strands at the base of Lessoniopsis littoralis which measured about i*i mm. 
in length. He has not remarked on the finer structure of the strands. The 
filaments, as the plant grows on, add to their number, resulting finally in 
a cluster of conical shape in general outline—the primary haptere. This 
process agrees in a striking manner with what has been observed in Chorda 
and Punctaria. Strompfelt’s 3 description of the formation of the primary 
haptere of Laminaria is in some points inapplicable to our case. 
Soon after the blade has extended its area by the stipo-frondal growth 
and its greater part has become distromatic, another layer of large 
parenchymatous cells makes its appearance. This layer originates from 
the transitional point between the blade and the stipe. So far as my 
researches extend, it has no direct genetic relation with the already existing 
two layers. In other words, the cells which constitute the new layer are 
generated at the transitional point from the internal cells of the polysi- 
phonous stipe. As a striking analogy, I cannot help mentioning, superfluous 
as it may seem, the mesoderm formation in the primary stage of an animal 
embryo. 
Fig. 21, PI. LIV, shows a cross-section through the upper part of the four¬ 
layered area of a frond about 1*5 cm. in total length. About the point a 
the axis passes; the right half and the left monostromatic marginal part 
are not shown in the figure. About b we clearly find the new layer interposed 
between the older two. The cells composing the latter still correspond to 
one another in their position, though somewhat more disturbed than before. 
Those of the new layer are quite different in size from those of the two older 
layers, and the septa are not at all related. At the point c we find a distro¬ 
matic portion without any layer interposed, and about d the lamina in the 
initial state. In the middle of the frond, the new layer is again split into 
two; each cell of one layer has its double in the other, showing that the 
two facing layers are sisters. These two new layers initiate both the cortex 
and the medulla in more advanced stages, as will be explained hereafter. 
Hence I prefer to assign the name c precortical layers ’ to them for the sake 
of convenience. 
Fig. 20 shows the cross-section of the same frond through the apex of 
the tristromatic area. Here we see the terminal cell of the new layer 
penetrating the apical portion of the distromatic area. 
1 Kutzing: 1 . c., Tab. XXV, I, Fig. 5. 
2 Griggs : Juvenile Kelps and the Recapitulation Theory. American Naturalist, vol. xviii, 
No. 506, 1909, p. 10. 
3 Strompfelt: Untersuchungen iiber die Haftorgane der Algen. Bot. Centralbl., Bd. xxxiii, 
1888, p. 398. 
