1916] ROE—SPLACHNIDIUM 405 
size of the organ, its unilocular nature, its single wall, the number 
of spores contained, the size of the spore, and the persistent empty 
case. On the basis of these features there is no reason why Splach- 
nidium may not equally well be considered as having unilocular 
gametangia containing isogamous gametes. This would give to 
Splachnidium a primitive position among the Fucaceae, but would 
offer for the Phaeophyceae a link in the phylogenetic sequence 
comparable to the position occupied in the Chlorophyceae. by such 
plants as Ulothrix. 
Moreover, in the Fucaceae the oogonia and antheridia are 
unilocular, no permanent walls separating the gametes. Also 
Drew (2) has reported conjugation of isogamous gametes in 
Laminaria digitata and L. saccharina. ‘The resulting zygospore 
divides and gives rise to a chain of cells which may represent the 
2x generation, and this in turn gives rise to the Laminaria plant, 
which represents the gametophyte, or x generation.” His observa- 
tions have as yet neither been verified nor disproved. 3 
Recently SauvAGEau (15, 16) has concluded from his investiga- 
tions that Sacchorhiza (and probably all Laminarias) presents a 
heterogamous sexuality with alternation of generations. The 
large plant is the sporophyte bearing uniform sporangia, and each 
sporangium develops like zoospores “which after transformation 
into embryospores oon eae ar gametophytes or female game- 
tophytes of t for life. The oosphere 
expelled from the female Oe. then fertilized, germinates 
at once and develops the plant of Laminaria.” 
In the contents of the reproductive sacs, therefore, as well as 
in form and origin of the conceptacles and in vegetative growth, 
Splachnidium is intermediate between the Fucaceae and the 
Laminariaceae. There seems to be no justification for establish- 
ing a separate family (10) with its main character “reproduction 
by spores contained in sporangia which are borne within 
conceptacles.”” 
urther investigation will doubtless show a much more intimate 
connection between the Laminariaceae and Fucaceae than is at 
Present recognized. Splachnidium may be placed with either 
group, since it has features common to both. Perhaps the presence 
