Holtz: OBSERVATIONS ON PELVETIA. 39 
that Pelvetia odgones divide into eight nuclei and that six of 
these are afterwards destroyed. Not more than four nuclei 
could be seen in the material studied. 
The ripe odgone contains two eggs. A delicate transverse 
partition is laid down across the middle of the odgonial con- 
tents. Each egg is hemispherical or round-conical in.shape. 
The lower one is often more pointed than the other. Nuclei 
could not be distinguished with definiteness. 
The o6gone increases rapidly in size, swelling to an oval or 
pear-shaped mass which surrounds itself with a thick gelatinous 
wall (/zgs. 36 and 37). The odgonial wall is at first not differ- 
ent from that of the basal cell, but it soon thickens and becomes 
gelatinous so that it swells inwater. This thickening continues 
till in the older odgones the swollen walls present the appear- 
ance shown in /7g. 37. Stratification is sometimes seen in this 
wall. 
In dehydrating specimens this gelatinous wall splits into two 
layers, a thin outer layer, and a thicker, firmer, more densely 
staining one. These layers often remain in contact at different 
points and generally at the base where both layers are thin (/7g. 
36). These two layers are the exochite and meso(endo)chite 
of Farmer and Williams.’ From their account it would seem 
that this double-layered condition is the normal. The obser- 
vations in this case, however, showed that the division of the 
oégone wall into two layers was unnatural. For nothing like 
it was observable in sections mounted in water or glycerine. 
‘The splitting is probably due to the tensions set up in the dehy- 
dration and the thicker mesochite layer is probably formed by 
the shrinking of the gelatinous middle substance upon the inner 
layer of the wall, therefore, being denser and appearing more 
intensely stained. A similar thing is noticeable everywhere in 
the dehydrated and stained pith. 
Antheridia. —It is generally possible to find oégonia in any 
section made through a mature conceptacle. The antheridia 
are often much scarcer, and search has sometimes to be made 
through several sections before they are found. ‘There is, how- 
ever, probably no conceptacle entirely without them. On the 
other hand, some conceptacles contain a great abundance of 
antheridia crowded in bunches among the odgones and para- 
‘Contribution to Our Knowledge of the Fucacee: Life History and: Cy- 
tology. 
