1906] SIMONS—SARGASSUM FILIPENDULA 163 
MATERIAL AND METHODS. 
Material for this study was collected near the shores of Woods 
Hole, late in July and during August. Plants both in vegetative and 
in reproductive conditions were abundant. The weak solution of 
chromacetic acid of Flemming (1 per cent. chromic acid 25°°, 1 
per cent. acetic acid 10°°, water 65°°) proved a satisfactory killing 
and fixing reagent. Microtome sections were cut from paraffin 5 » in 
thickness and stained either by iron-alum-haematoxylin after the 
method of Heidenhain or by safranin and gentian violet. The mucil- 
age on the surface of the plant and in young conceptacles and cryp- 
tostomata takes the anilin dyes readily, but is not especially trouble- 
some. 
GENERAL MORPHOLOGY AND HISTOLOGY. 
The habit of Sargassum filipendula is so like that of other species 
which have been described that it needs but slight attention. This 
species grows attached to rocks below low water mark, and therefore, 
unlike Fucus and Ascophyllum, is never exposed to the air. Vegeta- 
tive plants and reproductive plants bearing all stages of conceptacles 
are plentiful in summer. Sporelings are abundant also and easily 
collected, for the discharged eggs and their products, the sporelings, 
remain attached for some time by mucilage to the surface of repro- 
ductive branches near the parent conceptacles. 
The stem arises from a small disk-shaped holdfast and passes into 
long cylindrical branches which bear spirally arranged leaves, berry- 
like floats, which seem to be modified portions of teaves, as generally 
stated, and short reproductive branches. This form may attain a 
height of 60°™, but is commonly shorter. Cryptostomata develop 
upon stems, leaves, and occasionally also upon reproductive branches 
in Sargassum, which differs in this respect from Fucus, whose recep- 
tacles, according to Bower, contain no cryptostomata. 
KJELLMAN (’93) states that the conceptacles of Sargassum are her- 
maphrodite. In Sargassum filipendula both mature bisexual and 
unisexual conceptacles are formed. Some conceptacles contain only 
spermatocysts (antheridia); some, more rarely, contain many sper- 
matocysts and but one or two oocysts*(oogonia); and others bear 
only oocysts. The appearance of a conceptacle devoted to the forma- 
tion of oocysts differs decidedly from such a structure in Fucus. In 
