404 BOTANICAL GAZETTE [NOVEMBER 
In establishing a new family MitcHELL and WHITTING (10) 
summarize their reasons in the following statement (p. 8): 
While, then, the characteristics of Splachnidium rugosum are such that it 
can be placed in no existing natural order of the Phaeophyceae, its nearest 
allies appear to be the Fucaceae on the one hand and the Laminariaceae on the 
other. In its vegetative structure, in the nature of its thallus, and in the exist- 
ence of conceptacles, Splachnidium bears a resemblance to the Fucaceae; 
it differs from them, however, in its mode of growth, the former increasing by 
means of an apical meristem, while the growth of the latter is due to division 
of an apical cell. In the presence of an apical meristem Splachnidium 
approaches the Laminariaceae, but at the same time there is no plant in this 
order which has a cell corresponding to the remarkable cell found at the apex 
of the main axis and lateral branches of Splachnidium. In its reproduction it 
is allied to the Laminariaceae, and the production of sporangia within con- 
ceptacles might seem to point to a narrower limitation of the fertile sorus of 
plants of this order, recalling the difference between perithecium and apothe- 
cium in the fun: 
As to vegetative growth, the tissue of the thallus of Splachnidium 
bears an equal resemblance to the Fucaceae and the Laminariaceae, 
the only essential difference being in origin. Splachnidium and 
the Laminariaceae are products of a meristem, the former apical, 
the latter intercalary, according to the evidence of most authorities, 
and not apical as described by MitcHeLt and WuittiNc in the 
passage just quoted. The Fucaceae, too, are characterized by 
apical growth of the thallus, but all tissue is the actual result of 
segmentation of a definite apical cell. In vegetative growth, then, 
Splachnidium is intermediate between the two groups. 
The presence of conceptacles certainly seems a definite con- 
necting link with the Fucaceae; and yet some of the Laminariaceae 
show a tendency to approach this method of reproduction. SMITH 
and Wuirtinc (17) describe deep furrows in Macrocystis and Pos- 
telsia, which closely resemble conceptacles in form and origin. In 
this feature, too, Splachnidium is intermediate between the Fuca- 
ceae and the Laminariaceae. 
Morray (11, 12) and MrrcHett and Wuirttne (10) conclude 
that the reproductive sacs of Splachnidium are neither oogonia nor 
antheridia homologous with those of the Fucaceae, but are spor- 
angia homologous with those of the Laminariaceae, because of the 
