1900] OBSERVATIONS ON LESSONIA 325 
boldfast and continuous over its tip immediately under the epi- 
dermis, The epidermal cells and the layer underneath are the 
only ones that take a protoplasmic stain with avidity, but the 
layers within these, to the number of five or six, contain numer- 
ous sharply staining chlorophyll bodies. It is apparent, there- 
fore, that the growth in thickness of the holdfast ts essentially 
4 superficial, and its whole tissue is produced from the cambial 
aeas somewhat as is phelloderm from the cork cambium of 
higher plants. The epidermal cells proper are much the 
: smallest of all those that make up the holdfast area, averaging 
from $-lov in height. There is no differentiated medullary area 
in the organ. 
The longitudinal section of a haptere shows the customary 
Structure, and serves to make clear that the growth in length 
takes place in the same way as does the growth in thickness. 
Toward the center of the section the cells are much elongated, 
funning in some instances as high as one tenth of a millimeter 
mlength. This length diminishes toward the tip of the organ, 
and directly under the tip a vertical section does not differ 
“sentially in appearance from a transection. The dichotomous 
branching of the holdfast is due, as in Nereocystis and generally 
® Laminariaceze, to the appearance of adjacent circular fields 
. cambium which undergo division more rapidly than the 
Mervening and surrounding areas, so that the centers of these 
a protruded as the tips of the two new hapteri¢ 
ches, 
— eae hapteres which have become matted together ~ e 
e al holdfast mass, the walls are somewhat thickened in 4 
gg Many of the cells are collapsed and i ss 
engulfed ah whole hapteric branches seem 1 yee 
eg n the general tissue, reminding one of the me of the 
Otder, .. each other that often occur in other eS ‘aie 
thickenin 0€s not seem probable that there 1s ee ay 
Stipe of 4 of holdfasts or hapteres, such as takes piac embiing 
- these of 4 €ssonia, and produces the curious ings res 
N €xogenous tree. 
