44 MORPHOLOGY 
grains and oil drops. The complexity arises from the fact that the 
oogonium is closely invested by spirally wound elongated cells that 
arise from the cell beneath. Above the oogonium each investing cell 
cuts off a tip cell, the cluster of tip cells forming the so-called crown 
(figs. 115, 1 1 6). In fertilization the crown cells spread apart at the 
base, leaving five small slits, through which the sperms pass. Upon the 
formation of the oospore, the walls of the envelope cells thicken and 
harden, forming a nutlike spore case, which is the resting stage. Upon 
germination, the oospore sends out a simple filament and an elongated 
rhizoidal cell, a structure called the proembryo, and from the proembryo 
the adult shoot arises as a lateral branch. The adult plants, therefore, 
arise as lateral branches from a very different body. 
Conclusions. It is evident that the Charales cannot be related to 
the other green algae, since they differ strikingly in vegetative body, 
sex organs, sperms, and life history in all of which particulars the 
resemblances are rather with the higher plants. They should at least 
be isolated as a distinct group of Thallophytes, or preferably should 
constitute a group between Thallophytes and Bryophytes. 
(2) PHAEOPHYCEAE 
General character. The brown algae are almost all marine. They 
occur on all seacoasts, but are more abundant and conspicuous in the 
cooler waters. The forms exposed to tidal action have tough, leathery, 
and firmly anchored bodies, which sometimes reach such dimensions as 
hundreds of feet in- length. They are also often highly differentiated, 
both as to form and tissues. The nature of the characteristic pigment 
or pigments is in doubt. The green constituent may or may not be 
chlorophyll, but in any event there are also present certain brown or 
yellow constituents which give the characteristic color to the plants, 
referred to in the name of the group. It must not be supposed that all 
brown algae are necessarily brown, for there are gradations in the hue 
of the bodies from brown to olive green, but the characteristic brown or 
yellow constituents are always present. Two of these constituents have 
been separated and named phycoxanthin and phycophaein. Another 
general character of brown algae is that all the motile cells (zoospores 
and sperms) are laterally biciliate, in sharp contrast with the apically 
ciliate cells of most algae. 
The group is regarded as a highly specialized one, giving little or no 
indication of its origin. There is certainly no indication that it has 
