THE BROWN SEAWEEDS ОЕ THE SALT MARSH. 329 
the var. libera, and the dwarfing of the two embedded varieties. These are 
evidently correlated with the marsh habitat. 
The Marsh Forms of Ascophyllum. 
ASCOPHYLLUM NODOSUM, var. SCORPIOIDES, Hauck, var. MACKAII, Cotton, 
and var. MINOR, Turn. 
The first two algæ are in some ways the most interesting of all the Marsh 
Fucoids. The first is usually found embedded in the mud; but seems to be 
identical with the var. scorpioides, produced in the loose-lying associations 
characteristic of the Baltic. The relationships of these associations with 
those of the salt marsh will be discussed later (p. 339). There is no question 
Fra. 1.— Plant of Ascophyllum nodosum v. [ecad] scorpioides showing receptacles borne on 
long straggling branches. Nat. size. The Ray Marshes, Essex, April 1912. 
as to its status, for Reinke (1892, р. 11) and Oltmanns (1905, vol. ii. 
рр. 233 & 234) have described its origin by direct vegetative budding from 
fragments of typical Ascophyllum nodosum. 
The loose-lying var. Mackaii has often been considered a distinct species 
on account of its pendulous receptacles, which are borne on long branches. 
But Cotton is undoubtedly correct in designating the plant as a variety of 
A. nodosum, induced by external conditions ; for in the spring of 1912, and 
also 1913, we found the var. scorpioides fruiting in the Blackwater marshes 
(see fig. 1), and the receptacles are borne on long straggling branches, 
