178 Drew.—The Reproduction and early Development of 
in other works, but in all publications the reproductive areas are described 
as consisting of sporangia embedded among a mass of paraphyses. I have 
been forced to the conclusion that the organs so described are in reality 
gametangia. 
Briefly summarized, my results point to the conclusion that a number 
of planogametes are liberated from the gametangia, isogamous conjugation 
occurs, the resulting zygospore divides and gives rise to a chain of cells 
which may represent the ‘ 2 x ’ generation, and this in turn gives rise to the 
Laminaria plant, which represents the gametophyte, or ‘ x ’ generation. 
Summary of the more important Characters of the Plants. 
Laminaria digiiata grows on rocks and stones, from the level of the 
lowest spring tides to about the fifteen fathom line, and appears to be 
widely distributed in the temperate waters of the Northern Hemisphere. It 
is found all round the coasts of the British Isles and along the European 
seaboard from Norway to Spain. In the North Atlantic, it is found around 
the southern coasts of Greenland and along the American coast as far 
south as Massachusetts (Harvey). In the North Pacific it has been 
reported from Kamtschatka (Harvey) and Alaska (Setchell and Gardner), 
but is not found as far south as Japan. 
Laminaria saccharina grows in similar situations, from a little above 
the low tide mark to the five or ten fathom line. Its geographical dis¬ 
tribution is much the same as that of Laminaria digiiata , with the exception 
that it is not found quite so far south as the latter. 
The plant in both cases consists of a thallus, which externally shows 
differentiation into a flattened lamina, a rounded or oval stipe, and a root 
provided with a number of stout hapteres, by means of which the plant 
gains attachment to rocks. Internally, the thallus shows partial differ¬ 
entiation into cortical parenchymatous cells and a central or medullary 
region, consisting of cells somewhat resembling a tightly packed fungal 
mycelium. Mucilage canals are present in the cortex (Oltmanns). Growth 
takes place from an intercalary meristem, situated at the junction of the 
lamina with the stipe ; accordingly, when growth is proceeding, continuous 
additions are made to the base of the lamina and apex of the stipe. The 
length of the lamina remains fairly constant, owing to the constant erosion 
of the apex by wave action, whilst the stipe tends to increase in length with 
age. This continuous physiological growth ceases in the autumn, at the 
beginning of what may be termed the reproductive period. After this 
there is a rapid growth of the intercalary meristem with the formation 
of a new lamina, which has the old lamina still attached to its extremity 
(Setchell). Finally the old lamina degenerates and becomes detached. 
In L. digiiata , the lamina is broad and subdivided into a number 
of lobes by longitudinal incisions, its surface is smooth and uniform ; in 
