188 Drew, — The Reproduction and early Development of 
shorter, and several cells broad in the same stage of development. In later 
stages, when there is a partial differentiation into lamina and stipe, the 
lamina of L. saccharina is somewhat ovate, while that of L. digitata is more 
elliptical. 
As regards the productivity of the plants, in one experiment a piece of 
the reproductive area of L. saccharina , one square inch in area, was placed 
in 500 c.c. of the culture solution ; this was left for four days, then thoroughly 
shaken, and a subculture made with 1 c.c. of the solution. The resulting 
plants were much overcrowded, and probably only a small proportion 
developed. A rough estimate gave 4,000 as the number present after ten 
weeks. In the same proportion it is obvious 3,000,000 plants would have 
developed from each square inch of the reproductive area. 
Attempts were made to acclimatize plants grown in the modified 
Miquel’s solution to the tank water by successively adding larger and larger 
quantities of the latter. This, however, resulted in such a plentiful growth 
of various species of the Ectocarpaceae, and green Algae, that the Laminaria 
plants became smothered and did not long survive. Plants transferred 
direct from the culture solution to the tanks have, up to the present, lived for 
about nine months and average i-J to 2| inches in length, but their growth 
in the tank water is extremely slow, and they show a tendency to become 
eroded at the edges of the lamina. 
Summary of Results. 
There is direct evidence of the existence of conjugation between the 
bodies which have hitherto been generally called zoospores, hence it is 
justifiable to infer that they are in reality gametes, and are of the ‘ x' type. 
Consequently the zygospore formed by the fusion of the gametes must be 
of the ' 2 x’ type. 
The mass of cells produced by division of the zygospore may also 
be of the ‘ 2 type, but on the other hand the reduction division may 
occur in the early divisions of the zygospore. This point can only be 
settled by direct observations. Unfortunately, owing to the difficulty of 
finding a fixing agent which would permit of the treatment of the cells with 
a solvent for the colouring matter, without producing distortion, no cyto- 
logical work was done. 
Perhaps the fact that the young Laminaria plant arises as a direct 
outgrowth from the structure formed by division of the zygospore faintly 
suggests that the reduction occurs at an early stage in the formation of the 
mass of cells. 
For convenience of description I have alluded to this structure as 
the ‘ sporophyte ’, though this is scarcely justified on morphological grounds, 
and I have no cytological observations to support it. 
